Formulating for ILSAC GF-2 - Part 1: Obtaining Valve Train Wear Protection While Reducing the Phosphorus Content of a Motor Oil

The International Lubricant Standardization and Approval Committee (ILSAC) GF-2 requirements for Passenger Car Motor Oils (PCMOs) will lower phosphorus limits from a maximum of 0.12% allowed by ILSAC GF-1 to a maximum of 0.10%. In effect, the ILSAC GF-2 phosphorus limit removes 17% of the most commonly used antiwear and antioxidant additive in current PCMOs, zinc dialkyldithiophosphate (ZDP).

This paper outlines some work in ASTM Sequence V engine dynamometer tests to quantify the effect of reducing the ZDP on valve train wear and sludge formation. Engine data for the Sequence VE, the proposed Sequence VF, and the modified Sequence VE are presented. These three tests summarize the evolution of the Sequence V from the Sequence VE for GF-1 to the dual plug Sequence VE configuration for the GF-2 specification. Although the severity of the Sequence V test is shown to increase as the phosphorus level declines, ashless, nonphosphorus antiwear agents are shown to perform even better than the all ZDP 0.12% phosphorus formulations in the Sequence V engine test.