When talking about motor oils, there are two specifications that one needs to understand: API ILSAC and the European ACEA. Some use the two specifications interchangeably suggesting that the specifications are identical. There is, in fact, a great deal of difference between the two. Understanding what those differences are will highlight how oils are blended to meet specific emissions and engine requirements.
API ILSAC vs. ACEA
Let’s begin with a bit of background. Motor oils are a combination of somewhere between 70 to 90 per cent base oil (which can be a mineral, synthetic or an unconventional oil) and 10 to 30 per cent additives. The base oil has three main functions: to provide a viscous film that prevents metal-to-metal contact in an engine, to remove heat and to circulate the additives throughout the engine and its components. The additive package includes such things as low-temperature fluidity boosters, high-temperature viscosity boosters, anti-wear and friction modifiers, detergents and dispersants, and corrosion inhibitors.
In North America, oil specifications are decided upon by the American Petroleum Institute (API), a national trade association that covers the oil and natural gas industry across North America and the International Lubricant Standardization and Approval Committee (ILSAC), a joint effort of U.S. and Japanese automobile manufacturers. They decide on the performance standards that motor oils need to meet for the North American auto market.
In Europe, the European Automotive Manufacturer’ Association (ACEA) sets the performance standards for motor oils. The ACEA represents 15 European-based car, van and truck makers, and works with range of non-governmental, institutional and research partners. It cooperates with the European Council for Automotive R&D (EUCAR).
One of the obvious differences is that in North America the oil and gas industries have a say in how motor oils are to be formulated in order to meet vehicle requirements for emissions, efficiency and engine performance. In Europe, the vehicle makers have a great deal of input, pushing oil specifications to meet the specific performance requirements of their engine designs and to meet European standards for emissions and performance.
Another difference is in the prevalence of diesel fuel in Europe for passenger vehicles. In North America, diesel is still only used in a small percentage of passenger vehicles.
“In North America, there are mostly gasoline engines. In Europe, on the other hand, there are lots of diesel cars,” says Oliver Kuhn, research and development specialist with Liqui Moly. “So the European ACEA specifications have to take into account things like diesel particulate filters which lead to certain implications regarding the motor oil. As well, in Europe, car manufacturers are very influential. Regarding their oil specifications, they do not just follow ACEA standards, but go beyond them and issue their own oil specifications.”
Arnaud De La Hugues, product manager PCMO, Total Lubricants, says that the diesel specifications are a crucial one between API ILSAC and ACEA. “The last specification for diesel engines in North America, the API CF, is more that 20 years old today and diesel engines have evolved a lot in the past 20 years.”
“Another difference to take into account is the drain interval targeted,” Hugues continues. “In North America, the standard drain interval is between 8,000 km to 16,000 km whereas in Europe the average recommendation from car manufacturers is 20,000 to 50,000 km, or once every two years.
“When the API/ILSAC offers a one-specification-fits-all model, SN,GF-5, the ACEA proposes 10 different ones, A1, B1, A3, B3, B4, A5, B5, C1, C2 and C3, each with its own characteristics.”
Eni USA R&M Co Inc., makers of automotive lubricants and oils, wrote in a series of answers to questions submitted to them by SSGM that another difference comes down to the additive packages, that critical mix of lubricant enhancers and friction modifiers that blenders use to meet the requirements of engine makers and targeted specifications for performance and emissions.
“The engines which are used in the American specifications are General Motors and Ford of large displacement (3.6 to 4.6 litres) integrated by a Nissan 2.4 L engine and a lab engine. The engines used in the ACEA specifications are PSA, Mercedes Benz and Volkswagen engines of smaller displacement (from 1.4 to 2.2 litres), plus a Ford 4.6 L in common with API SN.
“Therefore, although the parameters evaluated by API and ACEA at the end of the tests may be nominally the same – i.e. engine sludge, cam wear, oil oxidation, engine varnish, ring sticking and so on – these are evaluated via different hardware, furthermore with different test procedures. As test and corresponding engines are different, also their ‘appetites’ – to use the jargon of oil formulators – are different, i.e. the oil properties needed to pass apparently corresponding tests are different.”
Liqui Moly’s Kuhn adds that at the most fundamental level, the API ILSAC specifications and the additive packages the oil blenders use are based on gasoline engines only, which makes sense as gasoline engines are the most common engines used in passenger vehicles in North America. “ACEA, on the other hand, is for gasoline and diesel engines. An ACEA oil has to be suited for both fuel types. An ACEA oil suited only for gasoline cars is not permitted. Diesel creates more contaminants therefore the oil needs more detergents than oil for gasoline engines only. This extra amount of detergents interferes with the API testing scheme and would make an ACEA oil fail the API test.”
Total’s Hugues adds that ACEA specifications for the additive packages also need to take into account the longer drain intervals which are at least twice the distance recommended in North America, as well as protecting diesel engine components, “[and] be compatible with particulate filters for passenger cars, which have a big impact with designing an ACEA additive package. This leads to the selection of different components to ensure, for instance, proper dispersant and detergent properties, but also protection of exhaust gas after treatment devices such as the diesel particulate filter.”
“Compared to API specifications, ACEA specifications have more of a focus on low viscosity, stay in grade oils with extended drain intervals which [are] rated for engines meeting Euro IV /Euro V emission requirements, and running under very severe conditions,” adds Antonio Ramos, manager, marketing with Veedol. “Some European auto manufacturer will demand even more technology-specific motor oil formulations for their vehicles. Some manufacturers say the industry standards are great, but we are going to go an extra step and formulate specific oils for our engine because we have a particular type of technology. And oil formulators have to meet those demands.”
Eni added in their comments that the “API is concerned with preserving gasoline devices (three-way catalysts) only, and this is addressed by limits on phosphorus and sulphur. On the other side, ACEA has a sub-set of dedicated specifications with wider, more stringent compositional limits, to preserve also the life of diesel particulate filters. In order to meet these specifications, the oils have to be formulated with a completely different technology. These are the so-called low-mid SAPS oils. SAPS is an acronym for the chemical and physical parameters for which these limits are posed.
“Another difference is related to some aspects which are peculiar of more concern for one of the two realities only. Unlike the ACEA, API tests the impact on the oil of ethanol, being significantly present in U.S. gasoline, and other aspects such as turbocharger deposits, behaviour of used oil at low temperatures and phosphorus volatility. European specifications, on the other side, do not address the above ethanol issues, but – unlike API – include some tests for which gasoline with five per cent FAME is used.”