Industry Strides toward GF-6

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GF-6, the next passenger car engine oil category proposed for first licensing in January 2016, is taking shape. Unlike its predecessors, it will be divided into two subcategories, one backward compatible and one not.

Predictably, the new category calls for improvements in fuel economy and fuel economy retention, engine oil robustness to protect engines in all global markets, and adjustment to chemical limits to allow improved performance while maintaining overall durability.

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But unlike previous categories, GF-6 will consist of two sub-categories, GF-6A and GF-6B. GF-6A is the natural progression from GF-5 and will be backwards compatible with earlier categories. It will consist of SAE 0W-20, SAE 0W-30, SAE 5W-20, SAE 5W-30 and SAE 10W-30. The minimum high-temperature high-shear viscosity for all GF 6A grades will be 2.6 mPa-sec.

GF-6B is a special category set aside for SAE 0W-new and SAE 5W-new viscosity grades now under development by the SAE J300 Viscosity Classification Task Force. These new grades are expected to carry a new and unique designation, and will not be backwards compatible with previous categories. According to industry sources, GF-6B will have the same performance requirements as GF-6A except for high-temperature, high-shear viscosity of less than 2.6 mPa-sec.

Simply stated, the viscosity of GF-6B, required for several new engine technologies, may be too low for older engines. And auto companies are concerned about misuse; people may buy it for the fuel economy claims on the label despite the SAE viscosity grade difference.

Industry groups developing GF-6 are discussing the new 6B designation and how it might be presented to the customer, but have made no proposals.

A new wrinkle in the effort to successfully introduce the new category is the adoption of a process patterned on the Diesel Engine Oil Advisory Panels system for developing new heavy-duty categories. A new group known as the Auto-Oil Advisory Panel will follow a process similar, but not identical, to the process currently used for PC-11, the heavy-duty engine oil upgrade now under development.

The Auto-Oil Advisory Panel, cochaired by Terry Kowalski of Toyota and Luc Girard of Petro-Canada, is intended to replace the ILSAC/Oil system outlined in Appendix C of API 1509 Engine Oil Licensing and Certification System – although it is essentially the same group of people.

The Panel set up three task forces: one to develop the test matrix design for new tests and limits, a second to develop funding for the new categories, and a third to work on Base Oil Interchange and Viscosity Grade Read-Across guidelines. All three are essential parts of the category development process.

ILSAC – the automakers – have proposed a number of changes to test limits that will apply to both GF-6A and 6B. Engine test limits for the Sequence VG (or equivalent) are to be tightened, reflecting a desire for better deposit control. Ford has offered a 2L turbocharged engine for the probable new test. The Sequence IV (or equivalent) sponsored by Toyota and the venerable Sequence VIII (CLR engine) test limits remain the same.

Engine builders have proposed significantly higher fuel economy limits for the Sequence VID (or equivalent). In addition, a new engine has been introduced to replace the current General Motors engine which is going out of production. Sources say the new engine is slightly mild when run according to current VID conditions and with current reference oils. With a new engine and the probability of procedural changes, the test will likely be renamed Sequence VIE.

Automakers proposed tighter limits on viscosity increase and piston deposits for the Sequence IIIG (or equivalent). However, it is not clear how this test will proceed. GM has offered a test and procedure but has indicated that it will not be an ASTM procedure and will be managed by GM.

In addition, ILSAC has proposed two new engine tests: a chain wear test and an aeration test. Hardware, procedures and limits are yet to be determined for these.

For the most part, GF-6A and 6B bench test requirements remain essentially unchanged from GF-5, according to industry sources. A proposal to reduce the volatility limit from 15 percent to 13 percent was eliminated, and the TEOST 33C test is not currently included, although provision is made for a possible replacement test.

Panel members are looking at questions about how the replacement for Sequence IIIG will impact bench tests for phosphorus retention and aged oil low temperature viscosity. A new bench test to measure low speed pre-ignition has also been proposed, but no test apparatus, test procedure or limits are identified.

The next Auto-Oil Advisory Panel meeting is scheduled for early August.