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ACEA versus API ILSAC oil specifications

ACEA versus API ILSAC oil specifications

On Reddit forums, I routinely see questions from European car owners asking why Americans change their oil so often compared to what’s done in Europe. They ask the question, implying that Americans are somehow being “duped” into changing their oil more often. That’s not the case at all. European cars have longer oil change intervals because they use a different oil than we use in the U.S.

Who sets API, ILSAC and ACEA oil specifications?

API and ILSAC specifications are determined by API and ILSAC with input from carmakers

In North America, oil specifications are determined by the American Petroleum Institute (API) 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 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.

ACEA specifications are determined only by the carmakers

In Europe, the Association des Constructeurs Europeens d’Automobiles (ACEA) sets the performance standards for motor oils. Fifteen European-based car, van and truck makers, and work with range of non-governmental, institutional and research partners. ACEA cooperates with the European Council for Automotive R&D (EUCAR).

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 big difference between U.S. and Euro oil standards 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.

Differences between API/ILSAC and ACEA oils

• API/ILSAC oils have separate designations for gasoline engines and diesel engines.

• ACEA oil must work with both gasoline and diesel fuels. In fact, an ACEA oil suited only for gasoline cars is not permitted. Since diesel engines create more contaminants than gasoline engines, ACEA oils have 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.”

• ACEA specifications for the additive packages also take into account the longer drain intervals which are at least twice the distance recommended in North America. The additives that provide the longer drain intervals must also protect diesel engine components, and be compatible with diesel particulate filters for passenger cars. As a result, ACEA additive packages use different components to ensure proper dispersant and detergent properties, while still protecting exhaust gas after treatment devices.

ACEA oils have to be formulated with a completely different technology. These are the so-called low-mid SAPS oils (see definitions below).

• ACEA specifications focus on low viscosity that stays in grade

• API is concerned with preserving the life of the vehicle’s three-way catalysts) only, so it limits phosphorus and sulphur content.

• API tests the impact on the oil of ethanol, turbocharger deposits, and the behaviour of oil at low temperatures and phosphorus volatility.

• ACEA oil does not address ethanol issues

Some terminology is important here

SAPS — Sulphated Ash, Phosphorus and Sulfur

SAPS is a common term used to describe a particular ratio of additive content in European engine oils.

Sulphated Ash

Metallic content that remains as a result of engine oil combustion. In other words, sulfated ash is the what’s left after engine oil’s anti-wear and detergent additives have degraded

Sulfated Ash deposits are non-combustible. They cannot be removed by regeneration, and will instead collect in the diesel particulate filters (DPF) or other exhaust aftertreatment device.

If the amount of Sulfated Ash is high, it will clog the DPF, causing the engine to lose power and not function properly. If may also form deposits on internal engine parts, which can damage the engine.


Phosphorus is an anti-wear additive that improves resistance to oxidation. Phosphorus forms a thin layer on metal surfaces, limiting friction of metal parts rubbing together.


Sulfur is a cleaning and anti-wear additive that helps in overall engine cleanliness, as well as providing anti-wear and antioxidant protection.

However, too high a concentration of Phosphorus and Sulfur content can poison and damage a vehicle’s catalyst converter, as well as lead to a buildup of Sulphated Ash in the engine and after treatment device

Differences between ACEA E, A, and B

The ACEA E4 and E6 are for extended drain intervals,

E4 is a full Sulphated Ash, Phosphorus and Sulfur (SAPS) and a E6 a Mid/low SAPS.

The ACEA E7 and E9 are for standard drain intervals where the E7 is a full SAPS and a E9 a Mid/low SAPS.

ACEA A/B The ACEA A products are for gasoline light trucks The ACEA B products are for diesel light trucks.

Diesel and gasoline engines need a different oil

Europeans drive diesel-powered vehicles versus American and Japanese gasoline-powered vehicles.  In Europe, most vehicles are equipped with diesel particulate filters (DPF) to reduce soot emissions, so the oils they use must be compatible with DPF systems to prevent DPF fouling. Since diesel engines create more contaminants, ACEA oils contain more detergents and dispersants than an API ILSAC oil would for comparable gasoline engines. The additional detergent would interfere with an API test, and would actually cause the oil to fail API testing schemes.

Due to the prevalence of diesel engines, ACEA requires that all oil must work with diesel and gasoline engines alike. In fact, ACEA does not even allow an oil specification for gasoline engines only. API and ILSAC, on the other hand, have separate oil specifications for gasoline and diesel oils.

Longer drain intervals mean different additive packages

In addition to working with both diesel and gasoline engines, the additive packages in ACEA oil must last throughout the longer oil change intervals specified by ACEA (12,500 to 31,000 miles). That’s an important point since neither API nor ILSAC specifies oil change intervals. That is left up to the discretion of the carmakers.

Differing emissions and fuel economy issues between ACEA and API ILSAC

ACEA oil specifications tend to focus on low viscosity and extended drain intervals to meet Euro IV/Euro V emissions requirements. ACEA oil is formulated to protect the life of the diesel particulate filters. API, on the other hand, is more concerned with developing oil specifications that protect three-way catalytic converters and meet higher fuel economy standards. So API oils limit the amount of phosphorus (anti-wear additives) and sulfur to protect the catalytic converter. API and ILSAC oil must also be formulated to work well with a high degree of ethanol content in the American fuel supply chain. ACEA oils do not even address the ethanol issue.

ACEA versus API ILSAC testing procedures

ACEA, API, and ILSAC engine test sequences measure the same parameters: engine sludge, cam wear, oil oxidation, engine varnish, ring sticking, etc. But the test engines and testing hardware are different between the ACEA and API ILSAC tests. So the oil needed to pass the tests must also be different.


Due to the prevalence of diesel engines in Europe, ACEA oils are formulated more to handle the demands of a diesel engine, meet the much longer drain intervals demanded by ACEA, while preventing harm to the diesel particulate filter systems. API and ILSAC focus more on working well with gasoline engines while protecting the catalytic converter, providing increased fuel economy and affording compatibility with ethanol and turbochargers.

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