The U.S. Department of Transportation (DOT) classifies brake fluid into four main categories i.e. DOT 3, DOT 4, DOT 5 and DOT 5.1. The primary differences are their composition and boiling points. (We have discussed brake fluid in detail in OilChat 27 and suggest you revisit it to refresh your memory). Discussions in this newsletter will be restricted to DOT 3 and DOT 4 brake fluids.

Since 2006 DOT 4 is the most common brake fluid used in cars and light commercial vehicles. This is due to higher brake system temperatures, as well as widespread use of anti-lock braking systems (ABS), Electronic Stability Programmes (ESP) and traction control systems (TCS). Nonetheless some (mainly older) vehicles still require DOT 3, but since it is no longer readily available the question is often asked whether one can use DOT 4 instead of DOT 3 brake fluid. Unfortunately there is no straightforward answer to the question.

Both DOT 3 and DOT 4 brake fluids are glycol-ether based and therefore these fluids can be mixed without compatibility issues. Brake fluids are exposed to very high temperatures during braking and and the U.S. Department of Transportation have therefore included minimum boiling points in their Federal Motor Vehicle Safety Standards (FMVSS) 116 brake fluid specifications:

There are no standard formulations for brake fluids, but DOT 3 generally includes about 80% glycol-ether while DOT 4 typically has 50 to 65% glycol-ether with 20-30% borate-ester to improve the high temperature characteristics of the fluid. And this is the reason for the confusion.

Older vehicles that are still on the road today may have had their brake systems designed before DOT 4 brake fluid was introduced. Some brake hoses used in these vehicles, particularly those with inner tubes made of SBR rubber, were found to be incompatible with certain DOT 4 formulations in laboratory testing. The suspect brake fluids appear to be ones with high borate-ester content. It is believed that these formulations permeate the inner tube and then react with the PVA reinforcement braiding to produce a viscous liquid which could build up between the layers of rubber and make the hose considerably weaker. Attempts to reproduce this problem in real life conditions have proven to be difficult though. Most vehicle manufacturers today, however, use a different rubber (EPDM) in their brake hoses which is much more resistant to permeation.

There are several 2006 and older vehicles on the road today that still operate perfectly with their original brake hoses, but when considering what can happen when brakes fail, it is better to be safe rather than sorry. Standard rubber brake hoses do not cost a fortune and are considered consumables, i.e. they need to be replaced. Most vehicle manufacturers recommend you do so at least every six years. This implies that the original brake hoses still fitted to 2006 and earlier vehicles are long overdue.

IMPORTANT: Glycol-ether based brake fluids are hygroscopic which means they absorb moisture from the atmosphere and need to be replaced at least every two years – see your vehicle owner’s manual. It is also important to remember that brake fluid is toxic and combustible and can damage the paintwork of your vehicle.

Blue Chip DOT 4 Brake Fluid is compatible with all materials used in the brake and clutch systems of late model vehicles and exceeds the boiling point requirements of FMVSS 116 as shown below:

If you have any questions about brake fluid, you are welcome to email us at info@bcl.co.za and one of our technical experts will respond to your query.

Informally viscosity is known as the ‘thickness’ of a fluid. If you pour water into a container with a hole at the bottom, it drains in no time. However, if you fill the same container with honey, it drains much slower. Reason is that the viscosity of honey is high compared to that of water. You can therefore say the viscosity of a liquid is its resistance to flow.

Informally viscosity is known as the ‘thickness’ of a fluid. If you pour water into a container with a hole at the bottom, it drains in no time. However, if you fill the same container with honey, it drains much slower. Reason is that the viscosity of honey is high compared to that of water. You can therefore say the viscosity of a liquid is its resistance to flow.

More formally, viscosity is a measure of the internal friction of a fluid. Most liquids are cohesive. Cohesiveness is the intermolecular attraction by which the molecules of the fluid are held together and result in the internal friction of the fluid. This internal friction must be overcome by some force for the fluid to flow. A fluid with low viscosity flows easily because its chemical structure results in little friction when the molecules are in motion. There are various methods to measure the internal friction or resistance to flow, with the following two being the most frequently used for oil:

Kinematic Viscosity:

In kinematic viscometers the fluid flow is driven by gravity. This means the weight or density of the fluid helps it to flow. These viscometers measure the time that the fluid takes to flow through a capillary section in a viscometer tube. Each viscometer tube has a capillary constant. To obtain the kinematic viscosity, you multiply the measured flow time by the capillary constant. The unit for kinematic viscosity is centistoke (cSt). 1cSt equals 1 millimeter squared per second (mm²/s). The standard reference temperatures for kinematic viscosity measurements of lubricating oil are 40⁰C and 100⁰C

Dynamic Viscosity:

Fluid flow is induced by an external force in dynamic viscometers. Rotary viscometers are frequently used to measure the  dynamic viscosity of oil. The test oil, kept at a stipulated temperature, is poured into the viscometer sample container and a spindle is inserted in the oil. The spindle is rotated at a specified RPM and the torque required to maintain the RPM is measured. The results are reported in centipoise (cP). 1cP is equal to 1 millipascal-second (mPa-s). Pascal is a unit of torque similar to kW and HP. Dynamic Viscosity is also known as Absolute  Viscosity.

 

In summary of the above we can say that:

• Kinematic viscosity is the internal resistance of the oil to flow and shear under gravity.
• Dynamic viscosity refers to the resistance of the oil to flow when an external force is applied.

Simply put, kinematic viscosity indicates how fast the fluid flows under gravity, while dynamic viscosity denotes what force is required to make the fluid flow at a certain rate. 

Kinematic viscosity incorporates fluid density as part of the measurement and therefore density provides a means to convert between kinematic and dynamic viscosity. The conversion formula is:

Kinematic Viscosity (cSt) x Density = Dynamic Viscosity (cP)

Kinematic or capillary viscometers are normally used to measure the viscosity of lubricating oils, typically at 40⁰C and 100⁰C. Rotational or absolute viscometers, however, are often employed for certain specific measurements. Multigrade motor oil is a typical example.

The viscosity grade of motor oil is specified by the Society of Automotive Engineers (SAE). Multigrade oils must conform to several viscosity requirements and their viscosity grade consists of two numbers, e.g. SAE 10W-40. The 10W represents the low temperature (Winter) specifications and the 40 specifies the high temperature requirements. The SAE Engine Oil Viscosity Standard J300 defines the limits for multigrade engine oils, using the following viscosity categories:

Kinematic Viscosity in cSt

• Low-Shear Viscosity at 100⁰C

Absolute Viscosity in cP

• Low-Temp Cranking Viscosity*
• Low-Temp Pumping Viscosity*
• High-Shear Viscosity at 150⁰C

*Temperature depending on viscosity grade.

In conclusion we emphasize that viscosity units of measure and viscometers are not restricted to what we have discussed above but we trust that this newsletter will clear some of the confusion around kinematic and dynamic viscosity.

If you have any questions about viscosity, you are welcome to email us at info@bcl.co.za

Over the centuries all sorts of materials have been employed as grease. In the very early days of the wheel animal fats were used as grease. It is believed that compounded grease was first used by the Romans and Egyptians on their horse-drawn chariots more than 3000 years ago. Grease from that era is thought to have been prepared from olive oil or animal fat mixed with lime.

It was not until the middle of the 1800’s that real progress was made with grease technology. During the First Industrial Revolution (1760 to 1840) the development of larger machines with tighter specifications running at greater speeds for mass production, triggered the search for more sophisticated and specialised greases. In response sodium based grease was formally invented in 1845. Lithium grease, discovered in the first half of the 20th century, was an even more advanced development. It was patented in the United States in 1950 and rapidly came into wide use as a multi-purpose grease.

In terms of use, lithium based grease is by far still the most popular type of grease today. Although it is suitable for a wide variety of automotive, industrial and other applications, lithium based greases should, however, not be considered as an all-purpose grease because their:

• Dropping point of less than 200°C is lower than various high-temperature applications
• Water resistance is not as good as some other grease types
• Adhesion properties are not all that suitable for sliding and reciprocating applications

In fact, there is not one grease type that is suitable as an all-purpose grease for every single grease application and hence the term all-purpose grease is misleading.

Moreover, the concept of “standardisation” is very attractive when it comes to reducing the number of lubricants in large operations. It is believed one can decrease the risk of accidentally using the wrong product by reducing the total number of lubricants in storage. Even more appealing is to reduce the inventory levels of lubricants that may only be used in a very specific application. While consolidation efforts are necessary to save money and reduce accidents, grease is often the focus of overenthusiastic consolidation.

While there are options available to reduce the number of greases in use, careful thought and consideration should be exercised to avoid over-consolidation and subsequent substandard lubrication for grease-lubricated components. After all, not all greases are the same, regardless of what the description may lead you to believe.

Q8Oils offers a comprehensive range of high-quality lubricants for a wide variety of automotive, construction, industrial, mining,  agricultural and other applications. For more information about the complete range of Q8 greases, phone 011 462 1829, email us at info@bcl.co.za  or visit www.bcl.q8oils.co.za.

Oxidation is a phenomenon that occurs in various formats around us every day of our lives. In simple terms oxidation can be described as a process in which oxygen combines with an element or substance – either slowly, as in the rusting of iron, or rapidly, like burning wood. Either way, oxidation has a variety of consequences. Some of its manifestations, like the combustion of fuels and the digestion of food in our bodies, are beneficial. Inversely many of its side effects are harmful, such as air pollution from burning fuels and food rancidification.

Likewise, oxygen has benefits and disadvantages for the human body. Every cell in our body needs oxygen to survive. Simultaneously some forms of oxygen are toxic to human cells and may produce a significant amount of the cellular injury that is associate with ageing and death, such as heart diseases and certain cancers. Little wonder humankind is consuming large quantities of antioxidants every day.

Lubricating base oils are also prone to oxidation but in this instance it only has undesirable effects.  The complex chemical reaction that occurs when oil combines with oxygen leads to increased viscosity, organic acids, the formation of sludge, varnish and deposits, additive depletion and the loss of other vital base oil performance properties. The ultimately result is reduced service life of the lubricant. The rate of oxidation is accelerated by the presence of water, acids, catalysts such as copper and, last but not least, high temperatures. In fact, the rate of oil oxidation doubles with every 10⁰C increase in temperature.

Antioxidant additives (also known as oxidation inhibiters) are incorporated into lubricant formulations to increase the oxidative resistance of the base oil and to maximize the service life of the lubricant. Antioxidants also allow lubricants to operate at higher temperatures than would be possible without them. Antioxidants retard the oxidation process but unfortunately nature is relentless and all lubricants will eventually oxidize to some degree. While antioxidants can significantly slow down the degradation of the lubricant in a machine, they do not last forever. Antioxidants are sacrificial additives that are consumed while performing their duty to control oxidation. Eventually all the antioxidant additives will be consumed, leaving the lubricant exposed to uncontrolled attack by the oxygen in the air.

The changes that are the most obvious in oxidised oil are a rancid smell and darkening of the oil. Other indicators can be visible in the viscosity and density of the oil. If you are still not sure you can do the following simple tests:

Blotter Spot:

A distinct brownish coloured outer ring around the deposit zone indicates the oil is badly oxidised – see OilChat 72 for details.

Interfacial Tension:

Place a drop of oil on the surface of water. If the oil drop spreads out over the surface of the water (instead of clustering up like new oil), it is a sign that the oil is oxidised.

All Q8 lubricants are formulated with high quality, oxidation stable base oils and proven antioxidant additives to maximise oxidative resistance and prolong service intervals. For more information about the complete range of Q8 high performance lubricants phone 011 462 1829, email us at info@bcl.co.za  or visit www.bcl.q8oils.co.za

A question often asked is can one use grease containing solid lubricants in wheel bearings?

Heavy duty greases fortified with solid lubricants are commonly used in arduous applications where  sliding or reciprocating motion is present. Typical examples are journal bearings, pins and bushes, guides, slides, sleeves and pivots. Solid lubricants prevent wear, scuffing/scoring, binding/sticking, and seizure very effectively in these applications. It is, however, debatable whether grease with solid lubricants is suitable for use in rolling bearings.

Molybdenum disulfide (moly) and graphite are the solid lubricants most commonly utilised in grease formulations. When a grease containing these ‘solids’ is used in high-speed rolling bearings, problems can be experienced with roller “skidding” when the rollers fail to rotate. The sliding of the rolling elements on raceways could lead to the following problems:

Overheating

As the rollers skid along on the raceways, they force the grease out of the way, resulting in metal-to-metal contact between the rollers and the raceways. This in turn generates heat and may well cause overheating of the bearing. Higher temperatures also reduce the hardness of the metal and can cause premature failure.

Flat Spots

When a roller skids, the wear on the roller is concentrated on the area where the roller is in contact with the raceway. As a result, the roller develops flat spots, and its service life is reduced. The raceway also wears, but the wear is spread out over a larger area and is therefore less severe.

Smearing

The removal and transfer of metal from one component of a rolling bearing to another is generally known as smearing. In severe cases of skidding the rise in temperature can be so drastic that it causes a collection of small seizures between bearing components.  Surface roughening occurs along with melting and the damage can quickly extend to the whole contact area. Various degrees of smearing can be described as scuffing, scoring or galling.

Greases containing moly are nonetheless recommended for some roller bearings that are subjected to very heavy loads and shock loading, especially bearings in slow or oscillating motion.  Typical examples are universal- and CV-joints. If in doubt, consult the equipment/vehicle/bearing manufacturer or your lubricant supplier.

Now back to the opening question Can one use grease containing solid lubricants in wheel bearings? Normally vehicle wheel bearings are adequately lubricated with a lithium based, NLGI 2, multipurpose or EP grease with oil viscosity 200 centistokes +/- 10%. For heavy duty applications a lithium complex grease will provide additional protection. Manufacturers generally do not recommend greases with solid lubricants for wheel bearings in highway applications.

But be warned, even if you are using the correct grease, skidding may occur. Over-greasing can also cause the rollers to skid on the raceways. As they slide forward, they push the grease out of the way, resulting in metal-to-metal contact, temperature increase and accelerated rate of oil bleed. This in turn will cause the grease to harden and hinder lubrication even more – leading to oxidation and bearing failure. 

Q8Oils offer you an all-embracing range of greases for an extensive range of application. For more information about our grease portfolio phone 011 462 1829 or email us at info@bcl.co.za. Our lubricant experts are at your disposal and ready to provide you with advice and answer any questions you may have. Alternatively you can visit www.bcl.q8oils.co.za.

Welcome to the eightieth edition of our newsletter. OilChat was introduced way back in October 2015 in response to requests and suggestions from our customers, distributors and our own sales team. The objective was a regular publication to share topical information about the oil industry, and lubrication in particular.

The topic of the inaugural issue of OilChat was Lubricating Base Oil since it is the foundation of most lubricants. The following editions of the newsletter focused on various basic subjects, such as viscosity, lubricant additives, oil formulations and lubricant specifications, to furnish our OilChat readers with a sound knowledge of the basics of lubrication. Thereafter lubricant applications were the key discussion subjects, with The Journey of Oil in the Engine one of the most popular topics.

More recently we have been writing about a broad range of lubrication related issues based on what is happening in the oil industry, new developments and topics of importance to everyone with interest in lubrication. Last, but certainly not least, some of the articles were based on questions and suggestions from you, our readers.

All previous editions of OilChat are still available on our website and are a useful encyclopedia of information on many aspects of lubrication and the oil industry. In fact, if you are au fait with the contents of all the newsletters you will be very much on par with delegates that have attended one of our Basic Lubrication Courses. To access our newsletters simply go to www.q8oils.co.za and click on the tab OilChats at the top of the homepage.

The newsletters are listed in numerical order but considering the number of OilChats that were issued since October 2015, it may be quite time consuming to find a bulletin dealing with a specific topic. To simplify your search we attach an index of all the OilChat topics we have published to date. In conclusion we wish to thank all OilChat followers for the loyal support of our forum. We want this newsletter to be of continued interest and value to you, so please share your feedback and suggestions with us to help us to improve your OilChat experience. Please mail any recommendations or questions that you may have to info@bcl.co.za or phone us at 011 462 1829.

INDEX OF OILCHAT TOPICS

No	TOPIC	No	TOPIC	No	TOPIC
1	Lubricant Base Oil	28	Automatic Transmission Fluid	55	Covid-19 and the Oil Industry
2	Viscosity and Viscosity Index	29	Borderline Pumping Temperature	56	AW vs EP additives Pt 1
3	SAE Engine Oil Viscosity Grades	30	Hydraulic Oil Selection	57	AW vs EP additives Pt 2
4	SAE Gear Oil Viscosity Grades	31	New Q8 Diesel Engine Oil	58	Chainsaw Lubrication
5	Industrial Oil Viscosity Grades	32	Total Base Number	59	Heat Transfer Oil
6	Industrial Gear Oil Classification	33	Cylinder Bore Polishing	60	Multigrade vs Monograde Oil
7	Engine Oil Composition	34	Cylinder Bore Glazing	61	Bicycle Service Products
8	API Petrol Engine Oils	35	Viscosity Index Improvers	62	API GL-6 Gear Oil
9	API Diesel Engine Oils	36	Detergent Dispersant Additives	63	UTTO vs TO-4 Fluid
10	Q8Oils Antwerp Blending Plant	37	Metal Working Fluid	64	All About AdBlue
11	ACEA Engine Oil Sequences Pt 1	38	Metal Working Fluid Management	65	Rock Drill Lubricants
12	ACEA Engine Oil Sequences Pt 2	39	Slideway Lubricants	66	To Flush or Not to Flush
13	API Gear Oil Classifications	40	Limited Slip Diff Lubrication	67	Contamination Destroys Hydraulics
14	Automotive Gear Oil Applications	41	Fuel Economy vs Engine Wear	68	Grease Intervals and Amounts
15	Lubricating Grease Pt 1	42	HTHS Viscosity	69	Overfilling Engine Oil
16	Lubricating Grease Pt 2	43	Lubricant Storage Life	70	Engine Oil Level Rising
17	Universal Tractor Lubricants	44	Two-Stroke Engine Lubrication Pt 1	71	Diptstick Oil Analysis
18	Flash Point	45	Two-Stroke Engine Lubrication Pt 2	72	Blotter Spot Engine Oil Test
19	ACEA Oil Sequences 2016	46	Two-Stroke Engine Lubrication Pt 3	73	Crackle Test for Water in Oil
20	Compressor Lubrication Pt 1	47	Soot in Engie Oil	74	Cavitation
21	Compressor Lubrication Pt 2	48	Engine Oil Deterioration	75	Gear Wear Pattern Analysis
22	Lubrication Regimes	49	Lubricant Aeration and Foaming	76	Oil Filter Analysis
23	Pour Point of Lubricating Oil	50	Base Oil Classification	77	Machine Health Checks
24	Grease Oil Separation	51	Chain Lubrication	78	The Danger of Water in Oil
25	Antifreeze Engine Coolant	52	Air Tool Lubrication	79	Extended Engine Oil Drain Intervals
26	The Journey of Oil in the Engine	53	History of Lubrication Pt 1	80	Index of Topics
27	Brake Fluid	54	History of Lubrication Pt 2

Regular oil changes are vital to the health of your engine irrespective whether you drive a small car or a heavy-duty commercial vehicle. In the past oil change guidelines required more frequent services. With advances in engine technology and enhanced oil formulations the drain intervals of engine oil have increased drastically – heavy duty diesel engine oils in particular.  ed.

Original Equipment Manufacturers (OEMs), the European Automobile Manufacturers’ Association (ACEA) and the American Petroleum Institute (API) have developed tests and specifications for long drain engine oils. Although these are designed to replicate real world use, the South African operating conditions are significantly more severe than in most other countries. Trucks operate in hotter environments, on rugged terrain, in areas of high dust, over long distances and, last but not least, with heavy loads.

Lubricant manufacturers often promote their high-performance engine oils (ACEA A3/B3 & E7, API CK-4 & SN, etc.) as Extended Drain or Long Life lubricants. In response the following question is frequently asked How long can I extend my oil change intervals? Alas, there is no simple and straight forward answer to the question. Engine oil is drained for two reasons:

• Additives are consumed during the life of the oil in the engine and may get depleted.
• To drain contaminants out of the engine when the used oil is replaced.

Very often the oil is contaminated beyond safe limits before the additives in the oil are depleted.

The following lethal contaminants can be root causes of premature oil degradation and engine failure:

Dust:

The ingestion of hard abrasive dust particles via the air intake system into an engine leads to rapid wear of engine components. Less than 100 grams of dust can severely affect expected engine life. A ten-litre diesel engine with a defective air filtration system spinning at 1400 rpm can breathe in up to 500 milligrams of dust per minute.

Fuel:

Frequent cold starts of an engine, excessive idling, cold running conditions and a defective fuelling system can lead to dilution of the engine oil with unburned fuel. Fuel dilution reduces the viscosity of the oil and also causes wash-down of oil on cylinder liners which accelerates ring, piston and cylinder wear.

Soot:

All internal combustion engines produce soot due to incomplete fuel combustion. It is a common misconception that soot does not occur in petrol engines, but it does. It is, nevertheless, not such a big problem in petrol engines as in diesel burners. The soot reaches the engine oil via blow-by past the cylinders. High concentrations of soot lead to viscosity increase, sludge, engine deposits and increased wear.

Water:

Frequent cold starts and extended periods of idling, especially in wintertime, causes water condensation in the crankcase. Water is one of the most destructive contaminants in lubricants. It attacks additives, causes rust, induces base oil oxidation and reduces hydrodynamic oil film strength. It also increases the corrosive potential of common acids found in used engine oils.

Glycol:

Most engine coolants contain glycol. It can get into the engine oil due to defective engine seals, leaking head gaskets, cracked cylinder heads, corrosion damage and cavitation of wet liners.

Glycol reacts with oil additives and causes precipitation. This affects the performance of the oil negatively. Less than one percent of coolant containing glycol in diesel engine oil is enough to coagulate/clot soot and cause a dump-out condition leading to sludge, deposits, oil flow restrictions and filter blockage.

Now back to the question How long can I extend my oil change intervals? It should be obvious by now that you need to know the condition of the used oil to determine suitable engine drain intervals. Various late model vehicles and construction equipment are fitted with telematic systems. Telematics combine GPS, onboard diagnostics, sensors and other technologies to record and transmit real time vehicle data that includes oil and filter health. This allows you to make decisions regarding oil drain intervals without waiting to bring the vehicle in to the workshop.

The majority of engines operating in South Africa, however, are not fitted with telematics and sensors to determine the condition of the oil, and oil analysis is the best tool to determine safe oil change intervals.  In addition, a good oil analysis program can also help reduce unscheduled downtime, improve reliability, extend engine life and reduce maintenance costs.

Finally, talk to your engine, filter and lubricant suppliers. At Q8Oils we have the people, products and proficiency to assist you to optimize your oil drain intervals, reduce maintenance costs and to extend engine life. Simply phone 011 462 1829 or email us at info@bcl.co.za. Our lubricant experts will be happy to answer any questions you may have.

Water in lubricating oil has been a point of keen debate for as long as oil analysis has been used to monitor lubricant and equipment condition. Water is one of the most destructive contaminants in most lubricants. It induces base oil oxidation, attacks additives, and interferes with oil film strength. Low levels of water contamination are not abnormal in lubricating oil, but higher levels of water ingression merit attention and the source needs to be investigated.

All lubrication systems  are susceptible to water contamination. Water can enter the oil through any opening – a crack or puncture, a poorly fitting filler cap, a loose inspection lid, an uncapped filling point, a busted seal or an open or damaged vent. Condensation is another common way for water to get into the oil – lubricating systems subjected to high temperature variations in particular. Equipment and machinery that are in direct sunlight are especially vulnerable to condensation when cooling down during the night. In addition, engine oil is disposed to water intrusion due to frequent cold starts and coolant leaking into the oil. Last but not least, water can be added to the oil by accident or human error.

Following is a brief  discussion of the harmful effects that water contamination has on lubricants:

Foaming:

Water is often a cause of foaming and air entrainment in lubricating oil. Foam is a collection of small bubbles of air that accumulate on or near the surface of the oil. In severe cases, the foam can leak out of the machine through breathers and dipsticks. Foam is an efficient thermal insulator, hence the temperature of the oil can become difficult to control. The presence of air bubbles in the fluid can also lead to excessive oxidation, cavitation and impaired lubricating properties.

Rust and Oxidation:

The presence of water in a lubricating oil can cause the progress of oxidation to increase tenfold. This may result in premature aging of the oil, particularly in the presence of catalytic metals, such as copper, lead and tin. It also induces rust and corrosion when in contact with iron and steel surfaces for extended periods of time. Rust can cause abrasive wear when a hard, rough surface slides across a softer one. Once an oil starts to oxidize, you may also see an increase in the acid number of the oil as discussed below.

Lubricant Degradation:

Water not only accelerates oxidation of metal surfaces, but also of the oil itself by depleting oxidation inhibitors within the lubricant. When oxidation occurs, acid formation can follow soon after. There is also the obvious change in viscosity. Add water to any other fluid, and the viscosity will decrease when hydrolysed. Hydrolysis is a chemical reaction where water breaks down the chemical bonds that exist within the oil. Conversely, if the water is emulsified into the oil, it can produce sludge, which will increase the viscosity. The ability of a lubricant to resist chemical decomposition in the presence of water is known as the hydrolytic stability of the oil. A lubricant will perform better in wet/humid environments when it has good hydrolytic stability.

Decreased Load Carrying Capacity:

The film strength of oil becomes impaired in the presence of water, Proper lubrication is dependent on the formation of a hydrodynamic oil film (see OilChat 22) to separate opposing friction surfaces. When pressure is applied to an oil film, the viscosity of the oil will increase proportionally to maintain protection. Water does not exhibit this tendency and will cause boundary lubrication where full fluid film/hydrodynamic lubrication would otherwise be present.

In journal bearings the presence of water can result in a loss of the hydrodynamic oil film strength that leads to increased wear. As little as one percent water in oil can reduce the life expectancy of a journal bearing by as much as 90 percent. For rolling element bearings, the situation is even worse. In addition to reduced oil film strength, the extreme pressures and temperatures generated in the load zone area of rolling element bearings can result in instantaneous flash-vaporization of the water. This promotes erosive wear.

Cavitation:

The phenomenon of cavitation is the formation and collapse of cavities (bubbles) in a liquid. Vaporous cavitation occurs when water vapor bubbles are formed in the low-pressure section of lubricating systems, e.g. on the suction side of the oil pump. When these bubbles travel to high pressure zones in the system they implode and condense back to the liquid phase. The collapse of the vapor bubbles can generate great forces and cause surface fatigue/erosion at the point of collapse. Read more about cavitation in OilChat 74.

Hydrogen Embrittlement:

Embrittlement is the loss of the ductility of a material, thus making it brittle. An embrittled product fails by fracture without deforming. Hydrogen embrittlement occurs when water in the oil finds its way into the microscopic cracks in the metal surfaces of components. When water is exposed to excessive pressure, it decomposes into its components (hydrogen and oxygen) and the hydrogen is released. This can force the microscopic cracks to open wider, and thus make them larger and more susceptible to fracture.

Water is a major cause of lubricant breakdown, poor machine reliability and component failure. Like all contaminants, it is important to take steps to control or eliminate the source of water ingression. To control moisture levels, one must be able to detect its presence. The crackle test is a simple test to identify the presence of free and emulsified water in oil. The crackle test was discussed at length in OilChat 73.

If you have any questions regarding this newsletter or any other lubrication related issues simply email us at info@bcl.co.za. Our lubricant experts will be happy to answer any questions you may have.

Doctors have perfected the art of conducting physical exams. They know what questions to ask and how to examine the body for clues that signify health, injury or disease. Maintenance staff, lubrication technicians and even equipment operators should be competent to perform ‘physicals’ as well. Like the doctor, they need to be aware of subtle changes or symptoms that might be an early sign of machine malfunction or accelerated wear.

One of the obvious problems with conducting such inspections is that for most machines, the critical operating components, including the lubricant itself,  are shielded from view by panels, casings, guards and housings. It is like asking your doctor to give you a physical while wearing body armour. Nevertheless, the machine and the lubricant can telegraph hints and signals in various ways and the selection of machine inspections should be tailored to the machine design and operating environment. This is done by selecting which inspections are needed and how frequently they should be carried out.

Following is a list of problem-revealing tests and inspections related to lubrication. They require limited technical proficiency and most of the tests involve no special tools or instruments.

Colour Change:

Monitor changes in lubricant colour with sight glasses and oil samples. Oils that have been subjected to high temperatures will exhibit marked changes (darkening) in colour and opacity. Many types of contaminants will alter colour as well. Additionally, a wrong lubricant can often be recognized by a change in darkness or colour.

Air Release Capability:

Most healthy lubricants will release entrained air readily. Distressed and contaminated lubricants may fail to release air from the oil and may also form sustained surface foam. Aeration and foaming (see OilChat 49) are not always oil related and may point to air entering the system or mechanical problems. Sight glasses and inspection hatches may provide the first sign of a problem.

Water Shedding Ability:

Water and oil usually do not mix. However, if they become conjoined in an emulsion, the problem is often associated with a change in the oil properties or contamination. Observing oil/water separation after violently mixing quantities of each in a sample bottle or laboratory glassware is an easy check for this property.

Blotter Spot Test:

This inspection involves placing a drop of oil on blotter paper and then observe how the oil spot ‘develops’. Healthy oil does not produce any structures and will spread out evenly on the paper, leaving a uniform gradient of oil colour behind. When the oil is badly contaminated, serrated patterns may form or the contaminants can clump together and do not migrate with the oil front. The Blotter Spot Test was discussed in detail in OilChat 72.

Sediment and Water:

It is often said that what is bad for the oil or material that has been removed from machine surfaces is also heavier than the oil. We know that substances heavier than the oil will settle out when mixed with the oil. That is why there is great wisdom in inspecting for water and sediment using drain port sampling.

Noise:

Few machines are quiet during operation. Even completely healthy machines have something to say. You may have heard the saying “a singing gear is a happy gear”. This is often true, but not always. Machine sounds change for specific reasons. Try to locate the point of generation. Some maintenance technicians play doctor by using crude stethoscopes in the form of a garden hose, a screwdriver or a steel rod held to their ear, with the other end touching potential noise-generating areas.

Temperature:

Doctors use thermometers but maintenance technicians employ a variety of tools including online temperature probes/thermocouples, thermal imaging cameras or handheld heat guns. A few common causes of temperature changes are wrong lubricants, degraded lubricants, contaminated lubricants, abnormal friction/wear – and the list goes on.

Pressure Change:

In the same way oil temperature can change in response to an assortment of problems, oil pressure can increase or decrease as well. Anything that can change viscosity or form surface deposits can change system pressure. For similar reasons it is no surprise that doctors pay special attention to blood pressure during an exam.

Filter Life:

There usually is a good reason when filters plug prematurely and it is worthy to investigate what is plugging the filter. Areas of particular concern are soft contaminants (sludge, organic material, dead additive residue, etc.), dust and wear debris. The filter is the final resting place for a variety of machine and lubricant operational waste products as discussed in OilChat 76.

You should have noted the many interesting human health analogies above, but this is just a start. There are far too many field tests and inspections to discuss in a publication like this. For those who make a living caring for the health of lubricants and machinery, the value of being capable to perform machine physicals is immense. Backed by laboratory oil analysis and other predictive maintenance technologies, the modern-day lubrication engineer and condition-monitoring professional is indeed fortunate to have such a ‘clear’ view of the internal state and operational health of his machinery. If you have any queries about Machine Health Checks, please email us at info@bcl.co.za. Our lubricant experts will be happy to answer any questions you may have.

 

An inspection of an used oil filter can be quite helpful to determine the condition of the engine. By dissecting a filter, you can discover information about the quality of the filter itself by checking for collapsed media, bad seals or weak points that may have formed in the filter media during use. You may also learn a lot about the health of the engine by analysing the debris caught in the filter.

The purpose of the oil filter is to trap contaminants suspended in the engine oil as it flows through the filter. This is accomplished by the filter medium inside the filter body. The medium typically allows the passage of very small particles (less than 5 microns) but traps the larger ones (greater than 5 microns). These are the ones you will find inside a filter when it is dissected.

If the filter is of the canister type, a simple and inexpensive method is to cut the filter housing open to remove the media. There are special tools available to do so. A typical example is shown on the right. Do not use a hacksaw since the metal shavings could be mistaken for wear metals. Once open, slice the filter media away from the centre tube with a sharp knife or razor blade. Lay the media out onto a clean surface and spread the pleats apart to look for any contaminants.

Filters prevent large particles from damaging the engine, but they also mask significant component wear from regular oil analysis. Following is a discussion of what you must look for in the filter media:

Ferrous Metals

Iron and steel particles are easy to identify because they are magnetic. Simply run a magnet across the particles to verify if they are ferrous. Iron and steel debris can originate from cylinder walls, camshaft lobes or the crankshaft. Abnormal wear of these components may release pieces into the engine oil and subsequently into the oil filter. Depending on the size of the pieces and the condition of the engine, you may want to inspect the components mentioned above sooner than later.

Non-Ferrous Metals

Many modern engines use lightweight aluminium components and pinpointing the origin of shiny aluminium particles in the oil filter can be difficult. One area that experiences regular wear is the piston skirt. Abnormal wear of the piston skirts is often due to contamination that has entered the combustion chamber or the use of the wrong engine oil. Checking the air intake and filter system is a good idea if you believe contamination has entered the engine.

 

Other small, shiny particles that can be confused with aluminium are tin, lead and copper. These materials are often used in the Babbitt alloy layer of the main and piston rod small end bearings. Insufficient lubrication of these bearings can lead to premature wear of the Babbitt layer and eventually to the failure of the bearing. If remnants of tin, lead or copper are found, it would be wise to ensure that the engine is being properly lubricated with the correct oil.

Non-Metallic Materials

In many cases, you will find some amount of carbon, which is difficult to identify, but the use of a magnifying glass can help. When rubbing carbon between your fingertips it will feel slightly gritty but it will break apart easily. Carbon accumulation is typically a result of blow-by getting past the piston rings. If your engine suffers from excessive oil consumption and low cylinder compression readings, you most probably have worn or damaged piston rings.

 

 

In many instances elements found trapped in the oil filter can point you in the right direction when attempting to diagnose an issue with an engine. Sometimes more information may be required and the filter will have to be sent to a professional laboratory for analysis. Either way the debris needs to be identified to take the necessary action to prevent possible serious engine damage.

At Q8Oils we have the people, products and proficiency to assist you with all your lubrication requirements. For more information phone 011 462 1829, email us at info@bcl.co.za  or visit www.bcl.q8oils.co.za. Our lubricant experts will be happy to answer any questions you may have.