Many engine oil marketers offer these cross-fleet products, and label them as API CI-4/SL, or CJ-4/SM in the API donut, for example. It is common, however, for universal oils to exceed the gasoline category’s phosphorus limit of 0.08 percent. This is because diesel oils through category CI-4+ have no limit on phosphorus content and CJ-4 maximum is 0.12%. API waives the gasoline category’s phosphorus limit as long as the marketer lists the C service category first.

The newly formed Auto Oil Advisory Panel, in addition to identifying new engine tests and limits for the GF-6 category upgrade, heard initial proposals early this year from the OEMs to eliminate universal oils, and the topic has been under discussion at succeeding AOAP meetings. AOAP’s members, which include automakers, lubricant marketers and additive companies, continue to debate the issue with little sign yet of consensus.

According to sources familiar with the deliberations, the automakers have proposed eliminating the API waivers which allow one oil formulation to cover both categories. Besides phosphorus limits, API waives the gasoline category’s Sequence VG, gellation index and ball rust tests for universal oils. If an oil passes these tests for the C category, the S category is deemed to be satisfied as well.

OEMs contend that C category oils are not designed for gasoline engines, and the higher phosphorus levels permitted in C category oils can damage catalysts in gasoline vehicles.

As well, the OEMs indicate, low-volatility phosphorus additives are not typically used in C category oils, which creates additional concerns about catalyst damage. They are also concerned that gasoline engine durability is questionable since some gasoline oil tests are eliminated for C category oils.

Especially, OEMs make the point that passenger car fuel economy can be adversely affected by the higher viscosities typical in C category diesel oils. The most popular viscosity grade for universal oils is SAE 15W-40, followed by 10W-30. The gasoline fleet in North America, by contrast, overwhelmingly uses 5W-30, 5W-20 or lighter “resource conserving” grades.

The oil industry, which oversees the API service categories, countered with a proposal to maintain the current tables in API Document 1509, Appendix G, which exempt all viscosity grades, except those covered by ILSAC’s GF-series oils (SAE 0W-20, SAE 5W-20, 0W-30, 5W-30 and 10W-30).

OEMs responded that they feel that the relaxation of limits on even non-GF viscosity grade oils will result in potential for misapplication.

In a further move to clean up the situation, the OEMs have gone on to propose eliminating older but still-active gasoline engine oil categories, such as API SJ, SL and SM. Their position is that only by eliminating these categories can there be assurances that obsolete oils will not inadvertently be introduced into their latest engine designs and potentially result in engine damage and catalyst failures.

Oil marketers object to this proposal on the grounds that such products are fully licensed and have stated performance. As well, SJ, SL and SM oils are in demand outside North America, in areas such as Asia, Africa and Latin America. Finally, these advocates point out, some OEMs continue to ask for older category oils, and eliminating categories does not eliminate the oil from the market.

To date the issue is still unresolved and continues to be scrutinized by both sides. The AOAP will next meet on Sept. 13.