Progress on Tests, Test Limits for GF-6


Work continues on a variety of tests, test parameters and engine and bench test limits necessary for completion of the ILSAC GF-6 passenger car engine oil category.

Much of the recent attention on GF-6 has focused on the Sequence IVB wear test and debate about its validity, but although the Sequence IVB is critical to moving the category to market, it is not the only business that needs to be finished. Much work is still needed to develop a complete specification for GF-6, including firming up test parameters and engine and bench test limits. Testing is also underway to settle rules for base oil interchange and viscosity grade read-across – rules that are critical both to GF-6 and to ensure that previous specifications such as API SN, SN PLUS, GF-5 and others can be maintained.

Base oil Interchange and viscosity grade read-across rules are critical to the successful deployment of engine oils today. API base oil interchangeability guidelines define the minimum physical and engine testing necessary to ensure that engine oil performance is not adversely affected by substitution of one base oil for another. The guidelines are based on engine test data, using different base oils, for both gasoline and diesel engine oil performance. Viscosity grade read-across (VGRA) is allowed under API 1509 as a means of reducing engine sequence test costs, by comparing certain engine test results across multiple viscosity grades.

Marketers have so many formulation choices, and most must utilize both API Group II and Group III base stocks for the majority of their engine oil offerings. They also need approvals for multiple base stocks to ensure efficient logistics and supply security. Without BOI/VGRA, marketers would need to run every test in every base stock or combinations of base stocks. It would be cost prohibitive to deploy products, and it would take a very long time because there would not be enough testing capacity to go around.

The BOI/VGRA task force chaired by Rick Dougherty of ExxonMobil, which has a $6 million budget, has already made significant progress.

The Sequence VIE BOI/VGRA test matrix is near completion, with runs at Afton Chemical, Intertek and SwRI already finished, and only testing in ExxonMobils lab left to complete. The Sequence VIE is needed not only for GF-6 but is also required to replace the Sequence VID fuel economy test so the industry can eliminate provisional licensing now in place for GF-5, SN and SN Plus resource conserving performance claims. Testing is complete for the Sequence VIF, which is required for SAE 0W-16 engine oils. Now the task force is reviewing the data and developing final rules for this test. Afton, ExxonMobil and Infineum presented proposals at the last meeting.

Testing was also completed for the Sequence VH test for protection from engine sludge and varnish. This test will replace the Sequence VG test and will be required to maintain existing categories as VG reaches the end of its life. Testing for the new Sequence X chain wear procedure is also complete. Data review and analysis to develop rules around these tests should proceed soon as well. The Sequence IIIH matrix, which will likely just cover VGRA, is also close to completion. It should also be noted that this team quickly developed the rules for the Sequence IX test for protection from low-speed pre-ignition, which was needed urgently for deployment earlier this year of SN Plus. Final plans should be developed soon for the Sequence IVB BOI/VGRA matrix, which remains key for keeping GF-6 on track for first licensing in the first half of 2020.

The GF-6 category is set to be divided into two specifications: GF-6A, which will be backward-compatible with GF-5 and previous specifications, yet would represent oils with better fuel economy and more engine protection; and GF-6B, which will offer similar performance, but will include the lower-viscosity SAE 0W-16 viscosity grade.

At the Auto-Oil Advisory Panel meeting on May 10, industry stakeholders also reviewed the proposed GF-6A and 6B categories test by test as a step toward setting final limits and test parameters. Most engine tests already have proposed limits and general agreement from all stakeholders, except for the Sequence IVB, which is still being worked on and will take some time to manage. Lubrizol questioned the need to maintain the Sequence VIII test for lead bearing corrosion for the GF-6B category. Since GF-6B is not backward compatible, the company asked if the Sequence VIII test is relevant to modern engines, and ILSAC agreed to consider this.

Besides engine tests, the GF-6A and B specifications also contains a number of bench tests carried over from GF-5. Precision of the Noack volatility test was a key topic, with ILSAC wanting to tighten down on the limit to ensure that commercial oils dont exceed 15.0 percent Noack volatility, as opposed to 15 percent, which allows for some test variability and may occasionally deliver oils that are slightly over 15 percent.

AOAP also discussed eliminating Simulated Distillation (ASTM D6417) volatility test as redundant and no longer relevant. Some concerns around the TEOST 33 high-temperature deposit test were discussed, along with an idea of revising rules for ASTM D7528, a bench test referred to as the ROBO test, which replaced the Sequence IIIGA for used oil low-temperature protection. Finally, Vanderbilt proposed eliminating or reducing the minimum phosphorus limit for GF-6. The company reasoned that doing so could allow for improvements in fuel economy, emission systems compatibility and chain wear protection. ILSAC was willing to discuss this idea but cautioned that it could impact Sequence IVB test limits and indicated that this was more of a possibility for GF-7.

The next major round of discussions will take place in Phoenix at the ASTM meeting during the week of June 25.