Mystery Clouds Fuel-economy Test


Why would two distinct GF-4 passenger car motor oils – which earlier had passed the rigorous Sequence VIB (Six B) engine test for fuel economy – repeatedly flunk the same test now? That’s the mystery facing ASTM and its engine test stewards.

The tests ASTM Surveillance Panel chairman, Charlie Leverett of testing company PerkinElmer, announced Sept. 17 that neither of two demonstration oils that motor oil companies had supplied as a potential reference oil for the Sequence VIB could perform at the GF-4 pass limits when run in calibrated industry test stands in multiple laboratories. The Sequence VIB is a test requirement for GF-4, the new passenger car engine oil upgrade that the American Petroleum Institute began licensing on July 31.

The engine oil industry was seeking a GF-4 level reference oil for the Sequence VIB at the SAE 5W-20 viscosity grade. Each of the two demonstration oils was tested five times, and neither made an average passing grade.

Moreover, Leverett noted, a review of current reference oil data does not indicate any severity trend which would have had an effect on the result of these oils at the time when they were run.

The failures are perplexing because the unnamed suppliers of each proffered oil had reported valid VIB test data, indicating good GF-4 performance. The failures are expensive, too. Each VIB test run costs nearly $25,000 and was absorbed by each participating laboratory, so together they represent an investment of $250,000.

Reference oils are used to calibrate engine test stands, and help ensure that every laboratory is running the test correctly. All other lubricant engine tests, both light- and heavy-duty, have at least one dedicated reference oil in our inventory, reports John Zalar, director of ASTMs Test Monitoring Center.

The failure of these oils as a VIB reference oil, emphasized Zalar, does not mean that Sequence VIB test stands cant be calibrated. Two other reference oils are available for this purpose.

ChevonTexacos Frank Fernandez, chairman of ASTMs Passenger Car Engine Oil Classification Panel, which has general oversight of issues relating to the quality of the specification, reported the VIB Surveillance Panel findings. He said, The panel speculates that GF-4 limits may have been based on insufficient initial data, and thus may be unrealistically challenging when weighed against an average of a large number of tests.

The Surveillance Panel is now at a standstill. Fernandez pointed out that the panel will consider another oil, if a company were to submit one, but would require all test result data from that company before such consideration. The cost to participating laboratories and the likelihood of success would have to be weighed prior to scheduling a series of tests on another oil.

In an attempt to move the issue off dead-center, Fernandez asked his group for ideas to pass on to the VIB Surveillance Panel and suggested five possible options:

1. Issue a solicitation to industry for any data which would provide clear evidence of a severity shift and suspend any decision on the currently proposed reference oils until further study.

2. Issue another solicitation for a GF-4 capable SAE 5W-20 reference oil, followed by the surveillance panel initiating another round of testing to confirm passing average GF-4 performance.

3. Request the surveillance panel evaluate proposed reference oils of another viscosity grade, and forgo a 5W-20 reference oil.

4. Accept that the industry has no GF-4 capable fuel economy reference oil, and move on with current oils.

5. Agree that GF-4 limits may be inappropriately severe, at least for 5W-20, and request that they be revisited by the ILSAC-Oil Committee.

Each option has significant implications, Fernandez noted dryly.

On Oct. 5, PerkinElmers Tom Franklin presented further information to the ILSAC/Oil Committee at its meeting in Detroit. Franklin, who chairs ASTM Subcommittee B, confirmed that both oils submitted as reference oil candidates were presented with full GF-4 credentials, that is, as having valid test data for all GF-4 tests, to the Test Monitoring Center. Seven laboratories volunteered five tests on each oil in calibrated stands.

One of the tested SAE 5W-20 oils, after five test runs, had summary results of 1.86 percent fuel economy improvement after 16 hours aging, and 1.70 percent improvement after 96 hours. Qualifying numbers for that viscosity grade are 2.3 percent and 2.0 percent. The other 5W-20 oil, after four test runs (one test was aborted), had summary results of 1.98 and 1.60.

Franklin offered some sobering information on the overall Sequence VIB candidate oil test performance to date. GF-4 candidate oils have a very low overall pass rate, something on the order of 10 percent, he said. His take on this matter? The bad news is that its difficult to get a GF-4 product into the marketplace. The good news is that any GF-4 product that does reach the market will have the best available fuel economy performance and meet the needs of consumers.

He also pointed out, If there had been a technology assessment period available during GF-4s development, as is now being considered for GF-5, this issue would have surfaced and been resolved earlier, before finalization of the category.

Bob Sutherland, of Shell Global Solutions (U.S.) Inc.,commented, This issue lends support for the [proposed] technology assessment period in GF-5. (See GF-5 Engine Oils: What, When, How? Lube Report, Oct. 13.)

Oils that display the API certification trademark must conform to the ILSAC GF-4 standard and would be expected to pass the test, stated Mike Riley of Ford Motor Co., which developed the Sequence VIB test. The ASTM Passenger Car Engine Oil Classification Panel and VIB Surveillance Panel will continue to review this situation.

There the matter rests.

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