Automotive Gear Oil Applications OilChat#14

This newsletter is in response to feedback from our readers. Following OilChat #13 we have received requests to elaborate on the composition and application of automotive gear oils; API GL-4 and GL-5 in particular. The most frequent question that comes up is “Can GL-5 gear oils be used in vehicles with synchronized manual transmissions?”

Modern high performance automotive gear oils (API GL-4 and GL-5) are formulated with oxidation and rust inhibitors, antifoam agents, pour point improvers and extreme pressure (EP) additives.The most common EP additives are sulfur-phosphorus (S-P) compounds that adhere to metal surfaces through polar attraction.

When subjected to heat and/or pressure (from a collapsing lubricant film) they react chemically with the metal surface to form a tough EP film. In general, the higher the GL rating, the higher the S-P content and the higher the EP protection provided.

Traditionally the engines of motor vehicles were placed in the front with a long driveshaft transmitting power to the wheels at the back – see Figure 1 below. A differential is used to let the power from the driveshaft make a 90 degree turn so it can get to the wheels via the side shafts (axles) – Figure 2. In days gone by vehicles were designed quite high on their wheels and the position of the driveshaft was not an issue. A crown wheel (large gear) and pinion (small gear) are used in the differential to ‘bend’ the power from the driveshaft to the side shafts (Figure 3). In this configuration the axis (center) of the pinion is on the same level as that of the crown wheel.  This design, however, became a problem when the height of vehicles was reduced to make them more streamline, since lots of interior space had to be sacrificed to accommodate the driveshaft tunnel – that hump that runs from the front to the rear in the floor of the vehicle. This problem was reduced with the introduction of hypoid differentials where the axis of the pinion is set below the axis of the crown wheel (Figure 4), resulting in a lower driveshaft.

 

Generally a differential with the axis of the pinion on the same level as that of the crown wheel (Fig 3) will be adequately lubricated by an API GL-4 oil although GL-5 will provide better protection.  Today, however, most rear wheel drive vehicles are fitted with hypoid differentials (Fig 4). Because of the increased sliding contact between hypoid gears, their contact pressure is higher and API GL-5 oils are required to lubricate these diffs effectively.

Most API GL-5 oils correctly claim they meet GL-4 requirements but does that make them suitable for synchromesh or synchronized transmissions? The answer is NO! They meet API Gear Oil specifications, not transmission oil requirements. The API GL-4 and GL-5 categories do not mention anything about transmission oil requirements, synchronized transmission in particular.

Synchronized transmissions are fitted with synchronizers to allow light and easy gear shifting and to eliminate that grinding sound, particularly when changing to a lower gear. Synchronizers use friction to match the speed of the components to be engaged during shifting. Slippery lubricants such as GL-5 hypoid gear oils can reduce the friction between the mating synchronizer surfaces and thereby effecting synchronizer operation negatively. In addition, synchronizers are often made of copper alloys. The way in which EP additives work can be disastrous to these ‘soft’ alloys. The S-P may attack the yellow metals chemically, causing synchronizers to fail prematurely.

Another question is why API Category GL-6 is obsolete when it offers protection from gear scoring in excess of that provided by API GL-5 gear oils? To answer this question we need to take a trip down memory lane.  Many years ago Ford required improved protection in certain of their pickup trucks and about the same time General Motors introduced a differential with a very high pinion offset.

This necessitated a higher gear oil service category and API GL-6 was developed to provide the greater protection needed. In fact the GM differential was used in the GL-6 test procedure. This level of protection is still claimed by some oil manufacturers, but can no longer be tested since GM have stopped producing these diffs. A shift to more modest pinion offsets and the obsolescence of API GL-6 test equipment have greatly reduced the commercial use of API GL-6 gear lubricants. Nevertheless, some manufacturers of high performance cars still specify this level of EP performance for their vehicles.

The photo on the left shows a brass synchronizer that had been damaged to such an

extent that it no longer “grips” its mating surface.  API GL-4 lubricants contain about half the S-P additives of their GL-5 counterparts. This means they do not react with synchronizers quite as aggressively but then they provide less wear protection for transmissions. This nonetheless is not a serious problem since there are no hypoid gear arrangements in synchronized transmissions.

What is then used in the transaxles of front wheel drive vehicles where the transmission and differential are combined in one unit? Oil selection is in

fluenced by the transaxle design:

  1. Contact surfaces of the gears are big enough to carry the load and less protection is required from the lubricant.
  2. Most transaxles are designed without hypoid gears.

Another question is why API Category GL-6 is obsolete when it offers protection from gear scoring in excess of that provided by API GL-5 gear oils? To answer this question we need to take a trip down memory lane.  Many years ago Ford required improved protection in certain of their pickup trucks and about the same time General Motors introduced a differential with a very high pinion offset. This necessitated a higher gear oil service category and API GL-6 was developed to provide the greater protection needed. In fact the GM differential was used in the GL-6 test procedure. This level of protection is still claimed by some oil manufacturers, but can no longer be tested since GM have stopped producing these diffs. A shift to more modest pinion offsets and the obsolescence of API GL-6 test equipment have greatly reduced the commercial use of API GL-6 gear lubricants. Nevertheless, some manufacturers of high performance cars still specify this level of EP performance for their vehicles.

In addition to API GL specifications, synchronized transmissions and limited slip differentials often have specific frictional requirements and reference should always be made to the equipment manufacturers’ oil recommendations for these units.

API Automotive Gear Oil Classifications OilChat#13

The API (American Petroleum Institute) defines automotive gear lubricant service designations to assist manufacturers and users of automotive equipment in the selection of transmission, transaxle and axle lubricants based on gear design and operating conditions.

Selecting a lubricant for specific applications involves careful consideration of the operating conditions and the chemical and physical characteristics of the lubricant. The API designations also recognize the possibility that lubricants may be developed for more than one service classification.

Gear oils are classified by the API using the letters GL (abbreviation for Gear Lubricant) followed by a number to identify the performance level of the oil. The API has also issued the MT-1 service designation for certain non-synchronised manual transmissions. Only three of the seven automotive gear lubricant service designations issued by the API are currently in use due to changes in manufacturers’ recommended practices or due to the unavailability of testing hardware.

The API Lubricant Service Designations for Automotive Manual Transmissions, Manual Transaxles, and Axles are described below, followed in some instances by supplemental comments (in italics) regarding the use of these lubricants:

API GL-1 (Obsolete)

This designation denotes lubricants intended for manual transmissions operating under such mild conditions that straight petroleum or refined petroleum oil may be used satisfactorily. Oxidation and rust inhibitors, antifoam agents and pour depressants may be added to improve the characteristics of these lubricants. Friction modifiers and extreme pressure additives shall not be used.

API GL-1 lubricants are generally not suitable for most passenger car manual transmissions. However, these
oils may be used satisfactorily in some truck and tractor manual transmissions. Lubricants meeting service designation API MT-1 are an upgrade in performance over lubricants meeting API GL-1 and are preferred by commercial vehicle manual transmission manufacturers.

API GL-2 (Obsolete)

The designation API GL-2 denotes lubricants intended for automotive worm-gear axles operating under such conditions of load, temperature, and sliding velocities that lubricants satisfactory for API GL-1 service will not suffice. Products suited for this type of service contain anti-wear or film-strength improvers specifically designed to protect worm gears.

 

API GL-3 (Obsolete)

This designation denotes lubricants intended for manual transmissions operating under moderate to
severe conditions and spiral-bevel axles operating under mild to moderate conditions of speed and load. These
service conditions require a lubricant having load-carrying capacities exceeding those satisfying API GL-1 service
but below the requirements of lubricants satisfying API GL-4 service.

Gear lubricants designated for API GL-3 service are not intended for axles with hypoid gears. Some transmission
and axle manufacturers specify engine oils for this service.

 API GL-4 (Current)

The designation API GL-4 denotes lubricants intended for axles with spiral bevel gears operating under moderate
to severe conditions of speed and load, or axles with hypoid gears operating under moderate conditions of speed
and load. Axles equipped with limited-slip differentials have additional frictional requirements that are normally
defined by the axle manufacturer.

API GL-4 oils may be used in selected manual transmission and transaxle applications where API MT-1 lubricants
are unsuitable. In all cases, the equipment manufacturer’s specific lubricant quality recommendations should be
followed.

API GL-5 (Current)

This designation denotes lubricants intended for gears, particularly hypoid gears, in axles operating
under various combinations of high-speed/shock load and low-speed/high-torque conditions. Frictional requirements for axles equipped with limited-slip differentials are normally defined by the axle manufacturer.

API GL-6 (Obsolete)

The designation API GL-6 denotes lubricants intended for gears designed with a very high pinion offset. Such
designs typically require protection from gear scoring in excess of that provided by API GL-5 gear oils.

A shift to more modest pinion offsets and the obsolescence of original API GL-6 test equipment and procedures have eliminated the commercial use of API GL-6 gear lubricants.

API MT-1 (Current)

This designation denotes lubricants intended for non-synchronized manual transmissions used in buses
and heavy-duty trucks. Lubricants meeting the requirements of API MT-1 service provide protection against the
combination of thermal degradation, component wear, and oil-seal deterioration, which is not provided by lubricants in current use meeting only the requirements of API GL-4 or GL-5.

API MT-1 does not address the performance requirements of synchronized transmissions and transaxles in
passenger cars and heavy-duty applications.

Automatic or semi-automatic transmissions, fluid couplings, torque converters, and tractor transmissions usually require special lubricants. Consult the equipment manufacturer or your lubricant supplier for the proper lubricant for these applications.

The API Automotive Gear Oil Classifications only specify performance level and service designation. Viscosity limits for automotive gear lubricants are described by the SAE J306 standard as discussed in OilChat #4.

ACEA Oil Sequences (part 2) OilChat#12

The ACEA Oil Sequences describe, amid others, “E” category service-fill oils for heavy duty diesel engines. These sequences define the minimum performance level for engine oils to meet ACEA requirements. Performance parameters other than those covered by the sequences or more stringent limits, may be specified by individual engine manufacturers – hence OEM specifications such as Mercedes-Benz 228.3, Volvo VDS-3, etc.

The ACEA Oil Sequences are subject to constant development to stay abreast of new engine designs, the increasing use of biofuels and more stringent emission requirements.

Each new issue of the sequences may exclude a previous sequence or include a new one, incorporate an increase in severity for an existing sequence or a change in testing method. As new editions are published older editions are withdrawn. The table below summarises the changes that have occurred since the first ACEA Oil Sequences were introduced in 1996.

 

ACEA intentionally omitted “E8” from the sequences.

A change in year linked to a specific sequence (i.e. E4-99 to E4-07) in the table above indicates a change in the sequence requirements. The four current ACEA Oil Sequences for heavy duty diesel engines are described below followed by a brief outline of the relevance of the sequence in italics:

E4 Stable, stay-in-grade oil providing excellent control of piston cleanliness, wear, soot handling and lubricant stability. It is recommended for highly rated diesel engines meeting Euro I, Euro II, Euro III, Euro IV and Euro V emission requirements and running under very severe conditions, e.g. significantly extended oil drain intervals according to the manufacturer’s recommendations. It is suitable for engines without particulate filters, and for some EGR (Exhaust Gas Recirculation) engines and some engines fitted with SCR NOx (Selective Catalytic Nitrogen Oxides) reduction systems.

UHPD (Ultra High Performance Diesel) category and the highest level of engine oil performance in the global heavy duty diesel market. Mostly SAE 10W-40 formulated with Group III base oils. Extended drain oils suitable for use in vehicles without a DPF (Diesel Particulate Filter). 

E6 Stable, stay-in-grade oil providing excellent control of piston cleanliness, wear, soot handling and lubricant stability. It is recommended for highly rated diesel engines meeting Euro I, Euro II, Euro III, Euro IV, Euro V and Euro VI emission requirements and running under very severe conditions, e.g. significantly extended oil drain intervals according to the manufacturer’s recommendations. It is suitable for EGR engines, with or without particulate filters, and for engines fitted with SCR NOx reduction systems. Designed for use in combination with low sulphur diesel fuel.

UHPD category and the highest level of engine oil performance seen in the global heavy duty diesel market. Mostly SAE 10W-40 formulated with Group III base oils. Extended drain low SAPS oils suitable for use in vehicles with or without a DPF.

E7 Stable, stay-in-grade oil providing effective control with respect to piston cleanliness and bore polishing. It further provides excellent wear control, soot handling and lubricant stability. It is recommended for highly rated diesel engines meeting Euro I, Euro II, Euro III, Euro IV and Euro V emission requirements and running under severe conditions, e.g. extended oil drain intervals according to the manufacturer’s recommendations. It is suitable for engines without particulate filters, and for most EGR engines and most engines fitted with SCR NOx reduction systems.

SHPD (Super High Performance Diesel) tier of mainly SAE 15W-40 engine oils designed for use in medium severity operations. Suitable for use in vehicles without a DPF. Often combined with API CI-4. 

E9 Stable, stay-in-grade oil providing effective control with respect to piston cleanliness and bore polishing. It further provides excellent wear control, soot handling and lubricant stability. It is recommended for highly rated diesel engines meeting Euro I, Euro II, Euro III, Euro IV, Euro V and Euro VI emission requirements and running under severe conditions, e.g. extended oil drain intervals according to the manufacturer’s recommendations. It is suitable for engines with or without particulate filters, and for most EGR engines and for most engines fitted with SCR NOx reduction systems. Designed for use in combination with low sulphur diesel fuel.

SHPD tier of mainly SAE 15W-40 engine oils designed for use in medium severity operations. Suitable for use in vehicles with and without a DPF. Often combined with API CJ-4. 

Claims against the ACEA Oil Sequences can be made on a self-certification basis. ACEA, however, requires that any claims for oil performance relating to these sequences must be based on credible data and controlled tests in accredited test facilities.

It is expected that new ACEA Oil Sequences will be issued during the third quarter of 2016. ACEA 2016 marks the first update since 2012, a break from the specification’s typical biennial update schedule. So what are some of the sequence changes that we can expect to see in ACEA 2016?

Biofuels. New fuel alternatives are becoming increasingly prominent, particularly the use of biodiesel fuels for the heavy duty market. These fuels can lead to increased oxidation, degradation and thickening of the oil. ACEA 2016 may therefore include new tests to assess lubricant effectiveness to prevent oxidation and deposit formation.

Seal Materials. Modern engines have introduced new elastomer sealing materials, necessitating an update of the seal test methods in ACEA 2016.

Soot. A new test may possible be added to assess oil resistance to soot-related thickening and deposits in diesel engines. The expected test will reflect the cleaner operation of modern low-soot heavy duty diesel engine oils.

In summary, modern diesel engines are being forced to become more fuel efficient, less polluting, and longer lasting. Subsequently their lubrication needs have changed dramatically since 2012. In addition, oil change intervals are being extended and the use of biodiesel is increasing. These changes require the use of superior heavy duty diesel engine oils. ACEA 2016 is expected to address all these issues and it is therefore not surprising that its pending release is anticipated globally with great interest.

Oil Chat will keep you UpToDate.

Always consult your vehicle owner’s manual to determine what engine oil you should use, and READ THE LABELS ON THE OIL YOU BUY.

ACEA Oil Sequences (part 1) OilChat#11

ACEA is the abbreviation for the Association des Constructeurs Européens d’Automobiles or the European Automobile Manufacturers’ Association in English. Among many other activities ACEA defines specifications for engine oils on behalf of the major vehicle manufacturers in the European Union.

The ACEA Oil Sequences were introduced in 1996 when they superseded the former CCMC (Committee of Common Market Automobile Constructors) specifications for engine oils. The ACEA Oil Sequences are the European counterpart of the API Engine Oil Classification System.

There are three principal categories within the ACEA Oil Sequences – “A/B” for petrol and light duty diesel engine oils, “C” for light duty catalyst compatible oils and “E” for heavy duty diesel engine oils. In this issue of OilChat the ACEA Oil Sequences for petrol and light duty diesel engines will be discussed. However, before this is done a few terms that are used in describing the Sequences need to be explained:

SAPS: (Sulphated Ash, Phosphorus, Sulphur) Phosphorus and sulphur comprise a significant portion of the additive content of engine oil. Sulphated ash is not added to oil; it is the result of additives in the oil leaving an ash residue when the oil is burnt under prescribed laboratory conditions.
DPF: (Diesel Particulate Filter) A device designed to remove diesel particulate matter or soot from the exhaust gas of a diesel engine.
TWC: (Three Way Catalyst) A catalytic converter that reduces the harmful Nitrogen Oxides, Carbon Monoxide and Unburned Hydrocarbons in the exhaust gas of (mainly petrol) engines.
HTHS: (High Temperature/High Shear rate viscosity) HTHS is indicative of the resistance of engine oil to flow in the tight tolerances between fast moving components in hot engines. It influences fuel consumption and wear in high shear regimes in an engine, such as those existing in piston ring/cylinder wall interface and the valve drive train. Lower HTHS viscosity generally means thinner oil which can improve fuel economy. Lower HTHS viscosity, however, usually comes at the expense of wear protection and therefore low HTHS oils are not suitable for use in all engines.

 

The current ACEA Oil Sequences were introduced in 2012 and may be condensed as follows:

ACEA A/B : Petrol and diesel engine oils

A1/B1 Fuel efficient oil for use at extended drain intervals in petrol and light duty diesel engines designed to use low friction, low viscosity and low HTHS oils. Unsuitable for use in some engines.

A3/B3 Intended oil for use in high performance petrol and light diesel engines and for extended drain intervals where specified by the engine manufacturer.

A3/B4 Intended for use in high performance petrol and direct injection diesel engines, but also suitable for applications described under A3/B3.

A5/B5 Fuel efficient oil for use at extended drain intervals in high performance petrol and light diesel engines requiring low friction, low viscosity and low HTHS oils. Unsuitable for use in some engines.

ACEA C : Catalyst compatibility oils

C1 Fuel efficient oil intended for vehicles with DPF and TWC. Formulated for high performance petrol and light diesel engines requiring low friction, low viscosity, low SAPS and low HTHS oils. These oils have a SAPS limit of 0.5% and are unsuitable for use in some engines.

C2 Fuel efficient oil intended for vehicles with DPF and TWC. Formulated for high performance petrol and light diesel engines designed to use low friction, low viscosity and low HTHS oils. These oils have a SAPS limit of 0.8% and are unsuitable for use in some engines.

C3 Fuel efficient oil intended for vehicles with DPF and TWC. Formulated for high performance petrol and light diesel engines designed to use low HTHS oils. These oils have a SAPS limit of 0.8% and are unsuitable for use in some engines.

C4 Fuel efficient oil intended for vehicles with DPF and TWC. Formulated for high performance petrol and light diesel engines requiring low SAPS and low HTHS oils. These oils have a SAPS limit of 0.5% and are unsuitable for use in some engines.

Note: Oils with a 0.8% SAPS limit may be referred to as mid SAPS.

To meet the stringent requirements of the above ACEA Oil Sequences, engine oils must pass fourteen laboratory and ten engine tests. Hence oils that conform to these ACEA standards are formulated with superior additive packages – even more so when the oil needs to meet API requirements as well. For instance, a well formulated engine oil can conform to ACEA A3/B4/C3 as well as API SM/SN. It is, however, not always possible for an oil to meet both ACEA and API standards. To illustrate, it is unattainable for an ACEA A5/B5/C1 performance level oil to meet API SM/SN, because A5/B5/C1 requires a maximum phosphorus limit of 0.05% whilst SM/SN specifies a minimum level of 0.06%.

Since the first ACEA Oil Sequences were introduced in 1996 new specifications were issued in 1998, 1999, 2002, 2004, 2007, 2008, 2010 and 2012. It is therefore obvious that the next issue of the ACEA Oil Sequences is now long overdue. Reasons for this delay are the replacement of obsolete tests with new ones to reflect engine technology advancements and also to address the complications associated with the increasing use of biofuels. It is expected that the new sequences will be issued during the second half of 2016 and that the new release may, among other changes, comprise the removal of A1/B1 and the introduction of a C5 category.

The ACEA Oil Sequences represent some of the most significant performance standards of the lubricant industry. Their influence and importance extend beyond Europe and since the pending update is a major step for the global lubricant industry, it is anticipated with great interest.

In conclusion it should be mentioned that ACEA itself does not test or approve any oils. They set the standards and oil manufacturers are responsible for having their oils tested in accordance to the prescribed standards. They may then make performance claims for their products, provided such products satisfy the relevant ACEA requirements.

Always consult your vehicle owner’s manual to determine what engine oil you should use, and READ THE LABELS ON THE OIL YOU BUY.

Compressor

Compressor lubrication part 1 OilChat#20

Compressor

A compressor can be described as a pump or other device that ‘inhales’ air and delivers it at a higher pressure. Compressors are also used to compress a variety of gases. The very first air compressor was the human lung. To illustrate, we use compressed air from our lungs to inflate balloons. In the early days of mankind our ancestors used their breath to stoke fires and to increase the temperature of glowing coals. With the advent of the Metal Age more heat was required to melt metals, such as gold and copper, and circa 1 500 B.C. a basic type of air compressor, called bellows, was invented. This device was a hand-held, and later foot-operated, flexible bag made of animal skin, that produced a concentrated blast of air that was ideal for achieving higher temperature fires. In 1 762 during the early days of the Industrial Revolution John Smeaton, an innovative engineer, designed an air blowing cylinder driven by a water wheel. It soon replaced the bellows in many industrial applications.

Today compressors are generally driven by electric motors, turbines or internal combustion engines. Modern compressors come in many designs and sizes, ranging from small units at petrol stations to inflate car tyres, to massive industrial machines that are too large to fit into an average-sized garage. The air pressure in car tyres is usually between 2 and 3 bar (29.0 and 43.5 pounds per square inch). The latest high-performance compressors can deliver pressures well in excess of 70 bar (more than 1000 psi).

Lubrication plays a critical role in the efficient and reliable operation of compressors. However, before we look at compressor lubrication, we need to understand the design and operation of the most common types of compressors available on the market. Compressors are divided into two main categories: Positive Displacement and Dynamic Compressors. Following is a brief discussion of the most popular compressors within these categories:

Positive Displacement Compressors

These compressors work by filling a chamber with air. The volume of the chamber is then reduced and consequently, the pressure in the chamber is increased. By nature of their design, Positive Displacement Compressors can deliver very high pressures. The most common Positive Displacement Compressors are:

Reciprocating Piston

i roReciprocating compressors function similarly to a car engine. A piston slides back and forth in a cylinder, which draws in and compresses the air, and then discharges it at a higher pressure. Reciprocating compressors are frequently multiple-stage systems, which means that one cylinder’s discharge will lead into the input side of the next cylinder. This allows for more compression than a single stage. Due to their relatively low cost, reciprocating compressors are probably the most commonly used compressors.

Rotary Screw

rrrrrThese compressors use two meshing screws (also called rotors) to compress the air. In oil flooded rotary screw compressors, lubricating oil bridges the space between the rotors. This provides a hydraulic seal and transfers mechanical energy between the driving rotor and the driven rotor. Air enters at the suction side, the meshing rotors force it through the compressor, and the compressed air exits at the end of the screws.

Rotary Sliding Vane

rotRotary vane compressors consist of a rotor with a number of blades (vanes) inserted in radial slots in the rotor. The rotor is mounted offset in a housing. As the rotor turns, the blades slide in and out of the slots, keeping contact with the wall of the housing. Thus, a series of increasing and decreasing volumes are created by the rotating blades to compress the air. Centrifugal forces ensure that the vanes are always in close contact with the housing to form an effective seal.

Dynamic Compressors

Dynamic compressors use very high speed (up to 60,000 rpm) spinning blades or impellers to accelerate the air. The increased velocity causes an increase in air pressure. Dynamic Compressors deliver large volumes of air but generally at lower pressures. The following designs are the most common types of Dynamic Compressors:

Radial Centrifugal

radiA rotating impeller in a shaped housing is used to force the air to the rim of the impeller, increasing the velocity of the air. A diffuser (divergent duct) section converts the velocity energy to pressure energy. Radial compressors are primarily used to compress air and gasses in stationary industrial applications.

 

Axial Flow

AxThese compressors use fanlike airfoils (also known as blades or vanes) to compress air or gas. The airfoils are set in rows, usually as pairs, one rotating and one stationary. The rotating airfoils (rotors) accelerate the air. The stationary airfoils (stators) redirect the flow direction, preparing it for the rotor blades of the next stage. Axial compressors are normally used where very high flow rates are required. By nature of their design, axial flow compressors are almost always multi-stage.

The majority of compressors requires some form of lubrication to either cool, seal or minimize wear of their internal components. Many compressors are adequately lubricated by premium-grade turbine oils. We will address the specific lubrication requirements of the above compressors in more detail in the next issue of OilChat.

ACEA oil sequences 2016 update

ACEA oil sequences 2016 update OilChat#19

ACEA oil sequences 2016 update

Since the first ACEA (European Automobile Manufacturers’ Association) Oil Sequences were introduced in 1996, updated specifications were issued in 1998, 1999, 2002, 2004, 2007, 2008, 2010 and 2012- please refer to OilChat numbers 11 and 12. The long awaited next issue of the ACEA Oil sequences was finally released during December 2016. Reasons for this delay were the replacement of obsolete tests with new ones to reflect engine technology advancements and also to address the complications associated with the increase in use of biofuels.

The ACEA Oil sequence comprises of three classes: one for Petrol and Light Duty Diesel engines, one specifically for Petrol and Light Duty Diesel engines with exhaust after treatment devices and one for Heavy Duty Diesel engines. The ACEA sequences make up some of the industry’s most important performance standards and the ACEA 2016 update is a significant step for the global lubricant industry. ACEA 2016 sets a substantial increase in required performance from ACEA 2012.

ACEA 2016 Changes compared to ACEA 2012

The main features of the new ACEA 2016 engine oil sequences are the optimized performance capabilities in relation to the latest engine technologies, compatibility with new elastomer materials (seals, hoses etc.), improved compatibility with biofuels and increased potential to reduce fuel consumption. Some additional tests were also introduced for the individual categories.

ACEA 2016 Specific Changes

  • Category A1/B1 has been removed and not replaced.
  • Category C5 has been introduced to address the reduction of CO² levels and fuel consumption.
  • Introduction of various new engine tests:
  • CEC L-107 sludge test has not yet been finalized. In the interim Daimler’s sludge test is being used.
  • CEC L-111 petrol direct injection test for piston cleanliness and deposits in turbochargers.
  • CEC L-109 oxidation test for engine oils used with biodiesel.
  • CEC L-106 oil dispersion test at moderate temperatures for diesel direct fuel injection engines.
  • CEC L-112 test to check oil/elastomer capability.
  • CEC L-104 engine oil performance test to measure the effects of biodiesel using the DC OM646 DE22LA engine for piston cleanliness and sludge.

The ACEA 2016 Oil Sequence comprise the following twelve different Performance Categories within the three Service Classes:

A/B: Petrol and Light Duty Diesel Engine Oils (High SAPS)

A3/B3, A3/B4 & A5/B5

C: Catalyst Compatible Petrol and Light Duty Diesel Engine Oils (Low SAPS)

C1, C2, C3, C4, C5

E: Heavy Duty Diesel Engine Oils

E4, E6, E7, E9-

The table below summarises the changes that have occurred for each of the ACEA Oil Sequences since 1996:

ACEA 1996 ACEA 1998 ACEA 1999 ACEA 2002 ACEA 2004 ACEA 2007 ACEA 2008 ACEA 2010 ACEA 2012 ACEA 2016
A A1-96 A1-98 A1-98 A1-02
A2-96 A2-96 #2 A2-96 #2 A2-96 #3
A3-96 A3-98 A3-98 A3-02 A1/B1-04 A1/B1-04 A1/B1-08 A1/B1-10 A1/B1-12
A5-02 A3/B3-04 A3/B3-04 A3/B3-08 A3/B3-10 A1/B3-12 A3/B3-16
B B1-96 B1-98 B1-98 B1-02 A3/B4-04 A3/B4-04 A3/B4-08 A3/B4-10 A3/B4-12 A3/B4-16
B2-96 B2-98 B2-98 B2-98 #2 A5/B5-04 A5/B5-04 A5/B5-08 A5/B5-10 A5/B5-12 A5/B5-16
B3-96 B3-98 B3-98 B3-98 #2
B4-98 B4-98 B4-02
B5-02
C C1-04 C1-04 C1-08 C1-10 C1-12 C1-16
C2-04 C2-04 C2-08 C2-10 C2-12 C2-16
C3-04 C3-07 C3-08 C3-10 C3-12 C3-16
C4-07 C4-08 C4-10 C4-12 C4-16
C5-16
E E1-96 E1-96#2
E2-96 E2-96#2 E2-96#3 E2-96#3 E2-96#5 E2-96#5
E3-96 E3-96#2 E3-96#3 E3-96#3
E4-98 E4-99 E4-99 E4-99#3 E4-07 E4-08 E4-08#2 E4-12 E4-16
E5-99 E5-99
E6-04 E6-04#2 E6-08 E6-08#2 E6-12 E6-16
E7-04 E7-04#2 E7-08 E7-08#2 E7-12 E7-16
E9-08 E9-08#2 E9-12 E9-16

ACEA internationally omitted “E8” from the Sequences.

 

Each new issue of the Oil Sequences may include a new sequence, an increase in severity for an existing sequence or a change in testing with no change in severity. the nomenclature used by ACEA as a suffic to the Category, depends upon the type of change.

The complete ACEA 2016 Oil Sequences Requirements and Test Methods are available on http://www.acea.be/uploads/news documents/ACEA European oil sequences 2016.pdf

flash point

Flash Point of petroleum products OilChat#18

flash point

In this issue of OilChat we will endeavour to clear some of the fallacies surrounding Flash Point. It is often believed that the Flash Point of a volatile liquid is the temperature at which the liquid will ignite (start to burn) spontaneously without an ignition source. This however is not true. Flash Point is defined as the lowest temperature at which a liquid (usually a petroleum product) will form a vapour in the air near its surface that will “flash, ” or briefly ignite, on exposure to an open flame.

Flash Point is an indication of the flammability or combustibility of a substance. The lower the Flash Point, the greater the fire hazard. The use of the Flash Point as a measure of the hazardousness of petroleum products dates back to the 1 9th century. Before the advent of automobiles, paraffin was the most sought after petroleum product which was primarily used as fuel for lamps and stoves. At the time there was a tendency by petroleum distillers to leave as much as possible of the commercially ‘worthless’ petrol in the paraffin in order to produce more product. This adulteration of paraffin with highly volatile petrol caused numerous fires and explosions in storage tanks and household appliances. In response legal measures were instituted to curb the danger, test methods were prescribed and minimum flash points were set.

You may well wonder why we sometimes find a variance when we compare the Flash Points of two similar products. The answer lies in the test method used. Flash points are measured by heating a liquid to specific temperatures under controlled conditions and then applying a flame to the vapour above the surface of the liquid. The test is done in either an “open cup” or a “closed cup” apparatus.

In the open cup test the sample is poured into a test cup that is completely open at the top. A thermometer is placed in the sample before it is heated. The test flame is passed over the cup at every 2 0 C increase in the sample temperature. When the sample vapours ignite momentarily the Flash Point is reached. The most commonly used test method is the ASTM D92 Cleveland Open Cup (COC) test.

In the case of the closed cup test, the sample is placed in a test cup with a sealed lid that opens when the ignition source (flame) is applied. The closed cup traps all the vapours that are generated during the heating of the sample and the vapours are not exposed to the atmosphere as they are in the open cup method. It is therefore no surprise that the closed cup test yields lower Flash Points than the open cup test. The ASTM D93 Pensky-Martens Closed Cup (PMCC) test is normally used to determine closed cup Flash Points. There is no set conversion factor for these Flash Point tests but PMCC is generally 5 0 C to 1 SC lower than COC for lubricating oils.

Flash Point is often used as a descriptive characteristic of petroleum products, and it is also used to help portray the fire hazards of liquids. It refers to both flammable and combustible liquids. There are various standards for defining each term but it is generally agreed that:

  • liquids with a PMCC Flash Point less than 37.8 0 C are flammable, and
  • liquids with a PMCC Flash Point higher than 37.8 0 C are combustible.

Although Flash Point primarily characterizes the fire hazards of liquids, it can also be an indicator of the quality of the base oils used in lubricants. In days gone by Flash Point was not really an issue but since the introduction of lower viscosity oils, such as SAE 5W-40 and even SAE OW-30, it became a more important consideration. The thinner the oil, the lower the Flash Point and the greater the tendency for the oil to suffer vapourisation loss at elevated temperatures. This results in the oil to burn off on hot cylinder walls and pistons in engines and thereby increasing oil consumption. A PMCC Flash Point of 2000 C is generally recognised as the minimum Flash Point for engine oil to prevent possible increased oil consumption at high operating temperatures.

If the open cup test is continued at increased temperatures after the Flash Point is attained, a point may be reached where the vapour continues to burn after being ignited. When the sample vapour sustains combustion, the Fire Point is reached. The Fire Point of a liquid can therefore be defined as the lowest temperature at which the vapour continues to burn (for at least five seconds) after being ignited by an open flame. The Fire Point for petroleum products is seldom listed, while Flash Point appears on most product data sheets. Generally, the Fire Point is about 1 O O C higher than the Flash Point, but if the value must be known, it should be determined experimentally. It should be noted that Fire Point testing is not undertaken in closed cup apparatus.

What many people perceive to be the Flash Point is actually the Auto-Ignition Temperature. Unlike with Flash Point and Fire Point, the Auto-Ignition Temperature does not need an ignition source. The Auto-Ignition Temperature of a substance is the lowest temperature at which it will ignite spontaneously in a normal atmosphere without an external source of ignition, such as a flame or spark. The Auto-Ignition Temperature (also known as Kindling Point) is a much higher temperature than the Flash Point and Fire Point.

tractors working

Universal tractor lubricants OilChat#17

tractor

This is not an optical illusion.

Tractors don’t come up on our radar screens all that often but modern farm equipment is a far cry from the “mechanical plow horses” of yesteryear. These new machines may still not break any speed record, but space technology is now being incorporated into agricultural equipment in the form of GPS devices, onboard computers, auto-steer system and even driverless technology!

Notwithstanding this array of state-of-the-art gizmos, lubrication still plays a critical role in the efficient and reliable operation of agricultural machinery. Tractors and other farm equipment, such as combined harvesters, have various components that need to be lubricated. These include the engine, transmission, final drives, oil immersed ( wet ) brakes hydraulic system and the power take-off ( PTO ). Just imagine the cost consequences if farmers had to stock different oils for all these applications. Furthermore, with so many lubricants in the oil store, there is also the risk of using the wrong oil for a specific component. It is therefore no wonder that agricultural equipment manufacturers and oil companies have worked together to come up with multifunctional lubricants:

Super Tractor Oil Universal (STOU/SUTO)

These oils fulfill several roles and make machine maintenance much simpler. They also reduce the number of lubricants farmers need to keep around because they can generally be used for all the applications mentioned above. When you peruse the product data sheet of a reputable STOU you will find that it meets the requirements of a host of Industry and Equipment Manufacturers’ (OEM) specifications. These may include, but are not limited to, the following:

  • Engines: API CG-4/SF
  • Gears: AP GL-4
  • Transmissions: ZF TE-ML 06A / 06B / 06C / 06G
  • Wet Brakes: Case MS 1317
  • Hydraulics: Eaton Vickers M-2950-S.

A STOU fluid can be described as a general-purpose farm lubricant with reasonable engine performance, fair load carrying capacity for gears and moderate hydraulic oil performance. However, as engines become more demanding, transmissions more sophisticated and hydraulic system pressures higher, trying to meet all the requirements with one fluid becomes more complicated. For instance, if a manufacturer recommends an API CI-4 performance level oil for the engine, two separate lubricants may have to be used since it is unrealistic to expect a single oil to meet API CI-4 and all the other service categories mentioned above. In such an instance it would be advisable to use a dedicated engine oil and a higher performance multifunctional lubricant for the other components.

Universal Tractor Transmission Oil ( UTTO )

These lubricants are also referred to as Tractor Hydraulic Fluid ( THF ) or Transmission, Differential and Hydraulic ( TDH ) fluid. They are used where the equipment manufacturer recommends a separate engine oil. UTTOshave no engine oil credentials, better hydraulic oil performance and improved wet brake fluid characteristics.

When you compare STOU and UTTO product data sheets you may well find they have some transmission, rear axle, wet brake and hydraulic oil specifications in common. However high-performance UTTOs will boast with OEM specifications that are unlikely to be met by STOUs such as:

  • Case MS 1207: Hy-Tran Plus, transmissions, hydraulics, wet brakes
  • Massey Ferguson CMS M 1141: Transmissions, hydraulics, highly loaded wet brakes
  • Volvo 97302-10: Transmission with built in wet brakes

As tractors become more sophisticated and require higher quality oils for satisfactory performance, there will most likely be an increased trend away from the all-purpose STOU fluid to a specific engine oil and UTTO combination.

TO-4 Fluid

UTTOs should not be confused with TO-4 fluids. UTTOs are mainly used in agricultural applications, although they are sometimes recommended for construction machines, such as Bell ATDs. TO-4 fluid originates from the Caterpillar TO-4 ‘Transmission Oil’ specification. TO-4 has become a standard term used within the industry for a specific type of additive/ fluid. TO-4 fluids normally meet Allison C4and other OEMrequirements as well.

Although both UTTOs and TO-4 fluids are designed for wet brake applications, they are not interchangeable since they have different frictional properties.Construction machinery, for which TO-4 fluids are intended, is normally much bigger and heavier than agricultural equipment. A higher level of friction is required to ensure that these heavy machines can stop on steep slopes, such as access roads down open cast mines.Tractor size, and therefore weight, is limited, as they need to use public roads, and therefore less friction is required to stop agricultural equipment. This results in TO-4 fluids having a higher coefficient of friction than UTTOs. Using the wrong fluid will mean that fluid/brake surface interaction will be affected and thereby reducing braking efficiency with possible catastrophic results.

Conclusion

Know your equipment manufacturer’s recommended lubricants, have them on hand and pay attention to tractor and equipment service intervals. If in doubt our experts are at your disposal, ready to provide you with advice and to answer any of your questions. For more information, please visit www.bcl.q8oils.co.za

drive shaft

Lubricating grease part 2 OilChat#16

drive shaft

Grease consists of a liquid lubricant that is mixed with a thickener ( see OilChat #15 ). Additives imparting special properties may also be included. Although is is liquid lubricant ( and certain additives) in the grease that provides the necessary lubrication, grease and oil are not interchangeable in their applications. The combination of the thickener, fluid and additives incorporated in grease produce certain properties or characteristics that grease does not share with lubricating oil.

The characteristics most commonly considered when selecting grease for a specific application included, but are not limited to the following:

Consistency is a key property of grease and is a measure of the relative hardness of the grease. Consistency is measured using a “penetrometer”. A cone is released and allowed to sink into the grease, under its own weight, for 5 seconds. The depth that the cone has penetrated into the grease is then read in tenths of a millimeter. The further the cone penetrates the grease, the higher the penetration result and the softer the grease. The National Lubricating Grease Institute (NLGI) has established consistency numbers ranging from 000 to 6, corresponding to specified ranges of penetration numbers. The table below lists the NLGI grease classifications along with a description of the consistency and how it relates to common foods:

NLGI 2 grease is the most common consistency used globally

Dropping Point is indicative of the heat resistance of grease. The Dropping Point is the temperature at which grease becomes fluid enough to drip under controlled conditions in a laboratory test. In general, the dropping point is the temperature at which the grease passes from a semisolid to a liquid state. This change is irreversible in greases containing conventional soap thickeners. Greases with materials other than conventional soap thickeners can, without a change in state, separate oil. The dropping point indicates the upper-temperature limit at which a grease retains its structure and NOT the maximum temperature at which a grease may be used. A good rule of thumb is to consider the dropping point minus 50°C as the maximum useful temperature limit.

Oxidation Stability is the ability of grease to resist breakdown in reaction with oxygen at elevated temperatures. Although both the base oil and thickener can oxidize, oxidation is more of a danger to the base oil. Oxidation turns grease into a sludge and causes gummy deposits to form on machine and component surfaces. Oxidized grease will become softer and appear darker. Prolonged exposure to excessive temperatures accelerates oxidation and can even result in carbonization where grease hardens or forms an abrasive black crust.

Structural Stability is a vital performance characteristic of lubricating grease as it is a measure of how the grease consistency will change in service when it is subjected to shear as a result of movement. Grease softening in a bearing may cause the grease are developed through careful selection of the thickness composition and effective manufacturing process.

Water Resistance is the ability of grease ti withstand the effects of water with no or little change in its ability to lubricate. Water can affect the grease stability resulting in hardening of softening. A drop inconsistency can cause the grease to be washed away from the bearing. In some instances, grease may also absorb the water and suspend the oil in the grease forming an emulsion that can reduce lubricity by diluting and changing grease consistency and texture. In extreme case water can displace the oil completely, causing the oil to leak away. In order to maintain its structure, the grease is required t have good water repellence in addition to adequate water tolerance properties.

Pumpability is an indication of how easily pressurized grease will flow through lines, nozzles, and fitting of grease dispensing system. Good pump ability characteristics are particularly important at low operating temperatures or when grease is used in automatic lubrication system where the grease is pumped through long lines from a central reservoir. If the temperature of grease is lowered sufficiently, It will become to viscous to flow and machine operation will be impossible. It is therefore important to check the recommended usable temperature range on the product data sheet when considering grease for arduous climatic condition.

Load Carrying Capacity is defined by the American Society for Testing and Material ( ASTM ) as the maximum load or pressure that can be sustained by a lubricating grease without failure of the sliding contact surfaces. In some circumstances the lubricating oil in the grease will prevent the breakdown of the lubricating fluid film under load, and only the action of anti-wear or extreme pressure (EP) additives in the grease will prevent surface contact and wear. in test to evaluate the load carrying capacty of grease, high loads are applied to moving surfaces that are in contact and lubricated by the grease. There are many test for determining the load carrying ability of grease, but the most commonly used ones are the Timken OK Load test and the Four Ball Weld/ Load Wear Index test.

When selecting grease fo a particular application all of these properties need to be compared to the requirenebts of the application. It could be disastrous to choose a grease based on NLGI grade only. The completed package of grease characteristics, including the fluid component viscosity, must be considered in order to choose the best grease for the job.

Important to remember is that all grease are not compatibile. It is therefore recommended that when changing from one grease to another, all the old grease should be cleaned out before the new grease is applied.