No GF-4 Until 4-04


The International Lubricant Standardization and Approval Committee, representing U.S. and Japanese auto makers, is postponing for one year – to April 2004 – its proposed introduction of the next generation of passenger car engine oils. ILSAC wants the new category, known as GF-4, to become mandatory by late 2004, but the American Petroleum Institute has not yet decided on a schedule for licensing the new oils.

Extending the deadline for GF-4’s initial marketplace entry has removed a lot of pressure from the decision-making process, but skirmishing over the core issue – the phosphorus content of engine oil and its impact on backward compatibility – continues nonstop.

In June, General Motor’s Bob Olree, chairman of the ILSAC/OIL committee – which includes representatives from auto, oil and additive companies and is developing the GF-4 Needs statement and technical specifications – said auto makers are still looking for a substantial phosphorus reduction for GF-4, below today’s limit of 0.10 percent. But he said that retaining GF-3 for an additional year wouldn’t make much of a difference in the long run because phosphorus’s effect on emissions systems is cumulative.

Brainstorming since then has been intense, with API, ILSAC and the American Chemistry Council each developing and ranking dozens of suggestions on GF-4’s phosphorus limit (from 0 to 0.10 percent) and backward compatibility options (from not to full).

On July 10, the ILSAC/OIL Committee met in Romulus, Mich., near Detroit, to do some weeding out. The meeting heard two technical presentations on phosphorus, and also heard an update on the new Sequence IIIG engine test for deposits, high-temperature oxidation and wear.

Another core issue aired at the meeting, of particular interest to the additives industry, is the likely category life: How many years will additive and oil companies have to recoup their investment in the new engine oil?

DaimlerChrysler’s Tracey King stated her company’s position unambiguously. With a phosphorus level of 0.05 percent and all other requirements as defined by ILSAC, we’d have no problem with a seven-year category life, she said. With 0.10 percent [phosphorus], we’ll start on GF-5 immediately. Silence by other ILSAC members suggested concurrence.

Valvoline’s Thom Smith narrowed the options for further consideration by API, ACC and ILSAC – setting phosphorus limits between 0.075 and 0.10 percent, with the understanding that this range would allow backward compatibility; a category life of between three and five years; and whether to include a measurement of phosphorus volatility.

The meeting heard two data presentations, as well. First, Ford Motor Co.’s Milt Johnson reported on a 20-car New York City taxicab test using Crown Victorias that were driven 100,000 miles, with their oil changed at 3,000 miles in the beginning and at 5,000 miles later in the test. Five oils were used. Two contained phosphorus at 0.093 percent and standard detergent packages; one had phosphorus at 0.093 percent and a non-detergent package; and two had a standard detergent package but were formulated with no phosphorus.

Ford tested the catalyst systems after 100,000 miles. After conducting FTP emissions tests, the close-coupled catalysts were analyzed by X-ray fluorescence spectroscopy to determine the amount of phosphorus contamination. Catalysts aged with detergent oils and 0.093 percent phosphorus carried 1.5 percent phosphorus by weight at the test’s end; catalysts aged with the non-detergent oil were found to have phosphorus levels equivalent to 2.6 percent; and those exposed to zero-phosphorus oils held only 0.05 percent. Big differences.

Tailpipe emissions increased in direct proportion to the level of phosphorus on the catalysts, Ford found.

Johnson summed up, The test demonstrated that oils with phosphorus at the 0.093 percent level deposit dramatically more phosphorus on the catalyst than phosphorus-free oils – and we saw far more tailpipe emissions, too.

Moreover, of the total amount of phosphorus that was lost from the oils during 100,000 miles, the fraction that could be attributed to selective volatilization of phosphorus compounds ranged from 56 to 87 percent. The volatility of engine oil phosphorus was a major contributor to phosphorus loading on the catalyst.

Ted Selby of Savant also reported on the volatility of phosphorus, expanding on data he presented earlier this year at the International Colloquium Tribology in Esslingen, Germany. He suggested that how much phosphorus is in the oil may not be as important as how much of it volatilizes and leaves the combustion chamber as part of the exhaust stream.

Considering the wide range of phosphorus volatility compared to the initial concentration in the fresh oil, he said, the choice of phosphorus chemistry and formulation should be able to produce low-phosphorus emissions. If so, engine oils having sufficient phosphorus additive content to serve the engine in preventing wear could have minor effects on the ability of exhaust stream catalyst to process emissions.

Selby pointed to test data from 1,300 oils collected in 1999 and 2000 by Institute of Materials, a Savant affiliate. The amounts of volatilized phosphorus collected from these oils, using the Selby-Noack volatility test (ASTM Method 5800C), showed very low statistical dependence on either oil volatility or phosphorus concentration in the fresh oil. The latter finding strongly indicated that chemistries of the phosphorus-containing additives [ZDDP] and their formulation with other additives were the controlling cause of phosphorus volatility and, by extension, emission level.

In other words, get the chemistry right and the phosphorus level becomes far less important, even irrelevant, in terms of catalyst poisoning.

Based on this analysis, Selby has developed a Phosphorus Emissions Index, a predictive measure of the amount of phosphorus an oil will release into the engine exhaust system.

Next, Selby divided the IOM oils into API categories SH and SJ, and applied this PE Index to them. He found substantially less (10 percent) phosphorus content in the SJ oils, but surprisingly when the PE Index data was averaged for the groups there was no difference between them in phosphorus volatility. In other words, API SJ/GF-3 had lowered phosphorus levels with virtually no impact on phosphorus volatility.

This is work at the bench, Selby emphasized. It is interesting and potentially important information. While very limited field tests tend to support its findings, more engine and field studies are wanted to confirm the tentative data.

Finally, the meeting heard about the upcoming matrix testing for the new GM-sponsored Sequence IIIG engine test, which measures deposits, high-temperature wear and oxidation.

Lubrizol’s Don Marn chairs the GF-4 Matrix Design Task Force. To evaluate test precision, he reported, 20 test runs will be conducted using five test stands and three prototype GF-4 formulations at Southwest Research Institute and PerkinElmer, the two San Antonio-based independent test labs. Half of these tests will be provided as Stand Calibration runs by these participating laboratories. The total cost of the remaining 10 tests is $350,000, or an average $35,000 per test. Actual testing should get under way as early as this fall, and be completed in six weeks.

Shell Global Solutions’ Ralph Cherrillo, chairman of API’s Task Force on Guidelines, reported on another testing component. Viscosity Grade Engine Testing [read-across] is also strongly recommended for inclusion in the matrix, as it provides a benefit to oil marketers and additive suppliers, he said, and a principle-centered approach should be used in designing the matrix. The base oil slate for the matrix testing has not yet been set, he noted, and will depend on the technology of the test oils selected by ILSAC.

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