AOAP approves ILSAC GF-7 passenger car engine oil specifications

The Auto Oil Advisory Panel (AOAP) has approved the final specifications for ILSAC GF-7A and GF-7B, the next generation of ILSAC passenger car motor oils (PCMO), to be licensed by the American Petroleum Institute (API) next year. The target date for first licensing is March 31, 2025.

The approval of ILSAC GF-7 fulfills an initial request made by the International Lubricant Specification Advisory Committee (ILSAC), a group that represents major automakers, in August 2022 and actively updated last year. At a meeting in December 2023, the AOAP reviewed additional data from the Technology Demonstration (Tech Demo) testing to establish that oils can meet ILSAC GF-7.

During a meeting at the Southwest Research Institute in San Antonio, Texas, U.S.A., on February 14, 2024, the AOAP accepted a motion to ballot the specifications for ILSAC GF-7A and GF-7B. The AOAP ballot was issued on February 16 and closed on March 18.

AOAP is an industry group consisting of gasoline engine manufacturers, oil marketers and additive suppliers. The group is responsible for the development of specifications requested by ILSAC, against which engine oil performance is certified and licensed by the API.

Michael Deegan, ILSAC chair, outlined the improved performance specifications in the ILSAC GF-7 request. ILSAC GF-7’s key performance improvements, beyond the current GF-6 category, are “fairly significant,” Deegan said.

• The Sequence IIIH test evaluates the oxidation stability of oil, its ability to maintain viscosity, and its effectiveness in protecting against engine wear and bearing corrosion under high-temperature conditions. Deegan highlighted the importance of elevated Weighted Piston Deposits (WPD) merit ratings, which indicate cleaner pistons. This is particularly critical given the increasing levels of turbocharging and higher combustion temperatures, which require precise oil formulations to prevent oxidation and carbon buildup in both the engine and exhaust systems. Deegan argued for a WPD merit rating of 4.6 or higher to ensure protection against the formation of carbon deposits due to oil oxidation. He expressed concerns about the adequacy of a WPD 4.4 merit rating, noting that it falls within the standard deviation of the existing WPD 4.2 merit rating, potentially indicating it may not offer sufficient protection.
• Sequence VI fuel economy improvements: Sequence VIE for SAE XW-20, XW-30 and 10W-30 and Sequence VIF for SAE 0W-16. The Sequence VIF engine test is tailored for the thinnest, low-viscosity oil graded as SAE 0W-16. These oils are formulated to offer enhanced fuel economy and are used in engines specifically designed to operate efficiently with lower viscosity oils, often in newer or more advanced engines that can benefit from such thin oils without compromising the engine’s long-term durability.
• Sequence IX Aged Oil LSPI (Low Speed Pre Ignition) engine test to assure protection for turbocharged, direct-injected, gasoline engines. The Sequence IX test is an important engine test to assess the ability of an engine oil to prevent LSPI in turbocharged, direct injection gasoline engines. LSPI is an abnormal combustion event that can cause severe engine damage, such as piston and connecting rod failures. To address this, the Sequence IX test comes in two versions: one using aged oil and the other using non-aged oil. The Aged Oil version provides insights into the durability and long-term effectiveness of the oil against LSPI. It assesses how well the oil maintains its protective properties under the stress of engine operation over time.
• Sequence X Chain Wear (CW) test enhancement by lowering the maximum % increase from 0.085 to 0.080. Also known as ASTM D8279, the Sequence X is a significant engine oil test designed specifically to evaluate the ability of an engine oil to protect against chain wear in automotive engines. This test is crucial because timing chain wear can lead to serious engine performance issues, including reduced efficiency, increased emissions, and potential engine failure.
• Lower new Oil MRV (Mini-rotary viscosity) viscosity of 40,000 centipoise (cP)
• New Seal Compatibility testing for ACM-2, AEM-2, AEM-3, and FKM-3 elastomers.

The NOACK volatility test—a test that determines the evaporative loss of lubricants in high-temperature service—remains unchanged at 15% at 250 degrees Celsius (250°C).

ASTM D874 Sulphated Ash Bench Test is a single decimal point 0.9% maximum limit in GF-7.

A new oil gelation test procedure, ASTM WK86363 (New Test Method for Measuring the Effect of Filterability of Engine Oils After Treatment with Water and Carbon Dioxide), is under development. The test, a modification of ASTM D6795 (Standard Test Method for Measuring the Effect on Filterability of Engine Oils After Treatment with Water and Dry Ice and a Short (30 min) Heating Time), was intended to address issues relating to oil gelation during extended vehicle storage.

Despite the importance of ongoing oil gelation testing, there is acknowledgement that the test may not be available by the proposed March 2025 first licensing date and may eventually be eliminated from GF-7. In the absence of the ASTM Gelation Test, AOAP has agreed to retain the gelation procedure in the GF-7 specification with the notation “If available at the time of licensing.”

An ASTM Surveillance Panel is tasked with clarifying when (or if) the test is deemed available. If a test becomes available later there has been no requirement to go back and requalify oils.

The adoption of ILSAC GF-7 was a technical process which took time. In the end the AOAP balloted ILSAC GF-7A with a minimum pass limit of WPD 4.6 merit rating and the Sequence VI Fuel Economy test, aligning with ILSAC’s original request to the AOAP.

With GF-7 specifying higher WPD and fuel economy, some AOAP members expressed unease about time to first licensing. The concern was that there was not enough time before GF-7 First Licensing, March 31, 2025, to assure market general oil formulations, with preferred technology and base stocks, are available.

The Engine Oil Licensing and Certification System (EOLCS) has a nominal one year waiting period before first licensing. The waiting period allows additive companies to complete and document engine oil formulations which have demonstrated GF-7 performance. Oil manufacturers will have time to procure and adjust their manufacturing to produce API certified GF-7 engine oil formulations before the first licensing date.

The standard waiting period is 12 months and ensures fairness in the marketplace when meeting the GF-7 first licensing date of March 31, 2025.

After first licensing, there is an “overlap” or “transition” period where oil marketers remain licensed to manufacture and sell existing licensed GF-6 inventory, to avoid wastage. During this time, oil marketers are expected to phase out, and not manufacture ILSAC GF-6 engine oils longer than necessary. Once the overlap period expires, the ILSAC GF-6 license is cancelled and only ILSAC GF-7 oils are licensed to be manufactured and carry the ILSAC certification. The Certification Mark, Starburst, is an evergreen mark which indicates that the oil meets the performance of the most recent ILSAC category. All engine oils displaying the ILSAC Starburst certification mark must meet the most current ILSAC category.

During a recent AOAP meeting, the Japan Automobile Manufacturers Association (JAMA), a trade organisation that represents the interests of the major automobile manufacturers in Japan, proposed to extend the GF-6/GF-7 overlap from one to three years, supposedly to facilitate a smoother transition to the new category.

Some AOAP members highlighted concerns that extending the overlap period could increase confusion in the marketplace, create service issues and lead to greater misapplication. The majority view from AOAP members is that there is no technical reason to extend the overlap period beyond one year.

Concerns regarding overlap timing lie beyond the technical ILSAC GF-7 standard. While the AOAP has the authority for the GF-7 timeline to First Licensing, extensions to overlap periods are licensing issues and part of the API EOLCS licensing procedure. However, AOAP can offer additional insights on GF-6/GF-7 overlap to API for evaluation.

The ILSAC GF-7 ballot determined the technical approval of the final ILSAC GF-7 specification. However, timing considerations did influence individual ballot decisions. The AOAP balloting process requires AOAP members to vote on acceptance of the ILSAC GF-7 technical standard. Ballot comments supporting the vote can address technical or editorial changes to ILSAC GF-7.

The GF-7 ballot closed on March 18, 2024. Several AOAP members cast negative votes, citing recurring concerns regarding WPD deposit ratings and the potential trade-off with fuel economy. Lingering uncertainties surrounding the gelation test compounded these concerns. Several JAMA members continued to express reservations on timing, advocating for more time to transition from GF-6 to GF-7 technology. They also repeated a previous request to extend the licensing of GF-6 beyond the standard one year after GF-7 first licensing.

During the AOAP review of ILSAC GF-7 ballot votes and accompanying comments, there was robust debate on resolving the key issues. During the AOAP review, a request was made to withdraw the negative votes based on the discussions; some positions were indeed revised. Toyota, in particular, expressed satisfaction with a commitment to ongoing dialogue around ILSAC GF-6/GF-7 licensing overlap period with API.

Other negative votes that focused on controlling timings were not accepted and in effect removed from the vote totals, with the AOAP Co-chairs Darryl Purificati of HF Sinclair Corp. and Michael Deegan of Ford Motor Co., reiterating the independence of AOAP’s technical specifications from such concerns. Similarly, issues relating to the already-completed technology demonstration period were considered resolved and set aside, noting that the technology had been sufficiently demonstrated.

Upon completion of the ILSAC GF-7 ballot review and adjudication, the ILSAC GF-7 specification moved to a passing ballot. The next meeting of the AOAP is scheduled in June during the ASTM Committee D02 (Petroleum Products, Liquid Fuels, and Lubricants) meeting in Austin, Texas, U.S.A.