The 2016 ACEA European Oil Sequences were formally released on December 1, 2016. The primary drivers for this edition were the replacement of obsolete tests, the introduction of new tests to reflect current engine technology and the need to address concerns about the impact of biofuels on lubricant performance. This article explores some of the key changes in the light-duty and heavy-duty lubricant sequences and their impact on formulating engine oils.

Heavy-Duty Sequences

While there have been no structural changes to the heavy-duty diesel sequences, a number of new and replacement tests have been introduced.

HTHS100: Dynamic viscosity at 100 degrees C and shear rate of 10 million s^-1 has been introduced as a rate and report requirement.

CEC L-109: This is a new oxidation test aimed at providing preventive protection against the effects of biodiesel-induced oxidation at elevated temperatures. The test parameters are oxidation and viscosity increase.

CEC L-112: This test replaces the current elastomer compatibility test with a suite of elastomers that are representative of current materials used by original equipment manufacturers.

CEC L-104: Also known as OM646Bio, this new test measures piston cleanliness in the presence of biodiesel in ACEA E6 and ACEA E9 categories. Ring sticking and sludge are report parameters, not official CEC parameters.

Mack T-8E: By replacing the Mack T-11 in the E9 category, the Mack T-8E is now allowed in all E categories. However, Mack T-11 results obtained as part of an API CI-4, CI-4 plus, CJ-4, CK-4 or FA-4 approval program can still be used in place of a Mack T8-E.

In practice, given the requirements of API and OEM specifications that are typically combined with ACEA E9 lubricants, it is likely that the Mack T-11 will continue to be used to support most ACEA E9 performance claims.

Light-Duty Sequences

In addition to new and replacement tests, the 2016 sequences introduce structural changes to the light-duty sequences. The introduction of the new C5 category has been long-awaited because no previous C category met the needs of OEMs for an aftertreatment-compatible lubricant with a high-temperature, high-shear viscosity of 2.6 to 2.9 milliPascal-seconds. This new category allows for the use of SAE 0W and 5W-20 lubricants, which are required to meet ever-increasing fuel economy requirements.

In terms of engine performance, C5 mirrors the requirements of C3, except for the M111 fuel economy requirements. C5 requires 2 percent better fuel economy compared to C3. The HTHS limits ensure that ACEA C3 and C5 claims are mutually exclusive.

ACEA has taken time to review the current sequences and has agreed, as a first step, to remove A1/B1 from ACEA 2016. This category is no longer required because C5 covers the lower viscosity grades and also provides the required compatibility with modern aftertreatment devices.

ACEA also added a new requirement to measure HTHS viscosity at 100 degrees C into the light-duty sequences in the belief that this temperature better correlates with fuel economy than HTHS measured at 150 degrees C.

ACEA 2016 introduces a number of new and replacement tests into the light-duty category.

HTHS100: The dynamic viscosity at 100 degrees C and shear rate of 10 million s^-1 has been introduced as a rate and report requirement in A5/B5 and all C-categories.

CEC L-109: As noted above, this new oxidation test provides preventive protection against the effects of biodiesel-induced oxidation at elevated temperatures.

CEC L-112: Again, this test is based on a suite of elastomers chosen to be representative of current materials used by OEMs.

CEC L-111: Also known as EP6, this engine test replaces the TU5 high-temperature oxidation engine test for the piston cleanliness parameter. Turbocharger deposits are included, but are not an official CEC parameter.

CEC L-106: This test replaces the CEC L-093-04 (DV4) oil-dispersion test. It measures viscosity increase at 5.5 percent soot and piston cleanliness. (Piston cleanliness is not an official CEC parameter.)

CEC L-104: Also known as OM646LABio, this new engine test measures piston cleanliness in the presence of biodiesel. Ring sticking and sludge are report parameters.

End of End-of-Life Tests

The TU5 high-temperature deposit and oil thickening test has been deleted from the ACEA 2016 light-duty sequences because the hardware for this test is no longer available. The EP6 succeeds the TU5 as the gasoline engine piston cleanliness test.

The TU3 valvetrain scuffing test was also withdrawn mainly due to limited TU3 hardware availability and its limited relevance to modern valvetrain designs.

Development Continues

Where current tests have reached the end of their life, or no longer represent engine technology in the field, replacement tests have been included in ACEA 2016. However, some additional test development work is still required.

The M271EVO, or CEC L-107 test for black sludge, was set to replace the current non-CEC sludge test, which was introduced as a stopgap when the M111SL sludge test became unavailable. There was unanimous agreement among industry stakeholders that a non-CEC or non-ASTM test is not a sustainable solution and that a test developed and controlled by CEC is preferable.

However, CEC L-107 test development experienced some unforeseen issues, and the test was not ready in time for inclusion in the ACEA 2016 release. For the time being, therefore, the ACEA sequences will continue to rely on the current M271 classic sludge test.

Current & Future Release

In Infineums view, the ACEA specifications provide a set of performance requirements defining oils that offer baseline protection for the majority of the European vehicle fleet. These oils, when used as recommended, are expected to run in vehicles without causing any problems and deliver a good quality lubricant on which marketers, OEMs and consumers can rely.

The specifications define a platform from which OEMs can build and a common baseline for lubricant developers. If individual OEMs require additional performance, such as extended drain intervals or more robust oils, this can most effectively be provided via their own in-house specifications.

The new sequences will replace the ACEA 2012 sequences as a means of defining engine lubricants with a first allowable use date of December 1, 2016. They become mandatory for new lubricant development from December 1, 2017, and lubricants with the ACEA 2012 claim may continue to be marketed until December 1, 2018. However, the work does not stop here.

Industry is already working to assess the need to replace the VW TDI, M111FE, TU3 and Sequence VG tests. The latter test is expected to need replacement during the lifetime of the new ACEA sequences.

The Sequence VG test is currently experiencing hardware availability issues and is expected to disappear in early 2017. This test is used in North American specifications and, as part of the API and ILSAC specification updates, a new Sequence VH, low temperature sludge test is being developed to replace the Sequence VG.

The M111 fuel economy test and the VW TDI test are expected to last until the end of 2017 or even beyond. But, due to limited hardware availability, they will eventually suffer the same fate as the TU3 and TU5.

Industry has its work cut out to develop all these replacement tests. Infineum will continue to support the development of high quality tests and monitor and report on progress.

Uwe Zimmer is Industry Liaison Advisor at Infineum International Ltd., based in Cologne, Germany.