ACEA Heavy Duty Engine Oil Specifications – An Insight

In order to comply with the ACEA 2022 HD oil specifications, suppliers have two years to update all Heavy-Duty Motor Oils (HDMO) that were available on the market at April 30th 2022. Products that were launched after April 30th, 2022, will have one year to ensure that they comply with the ACEA 2022 specifications.

Testing against the new OM471 piston cleanliness test can be a lengthy process. Developed by Mercedes-Benz, in co-operation with lubricant industry partners, the OM471 is designed specifically to test the performance of lubricating oils against piston deposits.

This test is time-consuming for two reasons. Firstly, the test itself takes six weeks to run and complete, and secondly, there is limited capacity with only a few laboratories who can run the officially recognised engine test.

If a product passes the OM471 first time, then suppliers simply document the results and move on. However, if the test fails, time is needed to reformulate the product, and this then requires more testing. So, timing can become problematic if initial tests run into an issue. 

It is also worth mentioning that OM471 is a very rigorous test, and passing it is not something that can be done without comprehensive research and development.

The OM646LA test checks engine wear and performance, specifically to ensure biodiesel compatibility in heavy duty trucks, and is based on engine performance. The test focuses on the biodiesel content of modern fuels, ensuring that engines and their lubricants are designed and protected against the additional challenges that biodiesel content within fuel encounters.

While these tests are still present in the 2022 HD oil sequences, and have in fact, become more stringent in recent years, it is interesting to note that these tests have been removed from the light duty engine 2021 sequences. The reason for this is due to the limited number of engines that are available in the industry to run the tests. 

In essence, yes, but each test is for a separate category. The E4 and E8 engine oil specifications, for example, use the OM471 test; E11 follows the Caterpillar C13 direct-injected turbocharged automotive diesel engine, also known as the Caterpillar-C13 Engine Oil Aeration Test (COAT); and E7 has the Caterpillar 1N test for piston deposit control. 

The tests have had to be split to incorporate different engine types from different manufacturers.

This is a common debate within the industry. There is currently no clear guidance from ACEA that suggests results from these tests cannot be used. Instead, there is a distinction made, referring to claims such as this as obsolete or retired specifications. 

An obsolete specification is a specification that has been replaced by a new version. A good example is the E4 2016, which includes Ultra High-Performance Diesel (UHPD) lubricants that are designed for use in severe duty, long-drain applications. E4 2016 has been replaced by the updated E4 2022, and therefore, the E4 2016 specification has been removed. 

It is currently accepted by ACEA as it is the latest specification of the E6. Once E6 2022 is made available, E6 2016 would be allowed for use until May 2024.

Texaco Delo 600 ADF is a low SAPS product, meaning it contains low levels of sulphated ash, phosphorus, and sulphur content. Products of this nature were formerly within E6 and E9 specifications, but since May 2022, they have become E8 and E11. It is our task to meet all the requirements defined in these low SAPS definitions.

Yes there are. If you look at E8 and E11, the limits on the biodiesel tests based on the OM646LA have definitely increased. This isn’t surprising with the truck and bus industry looking to use more biodiesel products in their transition from using diesel.

There are already tests taking place for internal combustion engines using hydrogen, but it is very much a work in progress, and we should make a distinction when we refer to hydrogen engines, this can also mean engines powered by a hydrogen fuel cell, which is a totally different prospect whereby lubricants aren’t needed as such. Hydrogen use in internal combustion engines is under review to see how it performs and how engine oils can help cope with any potential issues that show up as a result of this fuel type. 

No, not yet. In 2019, manufacturers had to report on the fuel economy of different vehicle types and will have to update this report again in 2025. Lubricant suppliers are collaborating with ACEA to identify an engine test that measures fuel economy.

In our discussions with ACEA, we are trying to determine the best method of measuring fuel economy, with both fresh and older oil. We need to ensure that the process is similar for all oils, so that there is a credible reference point. We must be able to examine if the engine ages in a consistent way, so that it replicates real world operations. There is still a lot of work to do to find the best method to really allow us to measure fuel economy for oils.

That's under review, current thinking is that we can use existing engine oils for LNG compatibility. 

LNG and HVO have typically been associated with smaller trucks and buses, and there is research being undertaken to investigate whether we should change the drainage or continue with the current specification, or we should develop new standards. This is already complicated for end users and fleets and remains an ongoing debate. 

In Europe, Original Equipment Manufacturers (OEMs) are focused on their own specifications, but ACEA often serves as a backup. Vehicle manuals will often refer to ACEA standards, so if there is a problem sourcing oil with the correct OEM specification, an oil will be found using the available ACEA reference. This stipulates which oil can be used until the engine’s next oil drain, which should be undertaken as soon as possible.

For older trucks, ACEA tests are still helpful because when vehicles are out of warranty or when OEM specifications become obsolete, the question becomes what can be used instead and so it is still appropriate to use ACEA tests as a safeguard in older trucks.

OEMs are currently working with both 0W and 5W products. 5W products already offer good protection levels and while 0W oils are more suited to very cool climates, they are also less cost effective. 

If you look at new OEM specifications, they are already geared towards both 5W and 0W products. A good example is MAN M3977, where both 0W and 5W oils can be used. 

Since there are no current oil specification limits on fuel economy or carbon dioxide emissions for heavy trucks, the industry has sought to implement +3.5 mPas high temperature high shear (HTHS) products. With these products, there would be no need for 0W oils.

There is a separate organisation which selects products from the market to evaluate against ACEA 2021 standards for cars and ACEA 2022 for trucks. These checks are on-going, and if the product does not meet the standards, SALE will bring it to the manufacturer’s attention and notify them that it needs to be rectified. 

Recent seminars run by The Technical Association of the European Lubricants Industry (ATIEL), have seen requests that these checks become more stringent and that a list of non-conforming parties be publicised. 

Texaco’s advice is, if in doubt, check with your supplier. ACEA requires that claims against the ACEA oil sequences can only be made by oil companies or distributors who have signed the EELQMS oil marketers’ Letter of Conformance, which can be verified on the ATIEL website.