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The ACEA Oil Sequences were introduced in 1996 when they superseded the former CCMC (Committee of Common Market Automobile Constructors) specifications for engine oils.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.