Factors influencing Lubricant Performance in the Sequence VE Test

In the Sequence VE test, combustion-derived contaminants provide the dominant stress on the lubricant's ability to maintain engine cleanliness and prevent wear. Contamination levels in the Sequence VE test are as much as twice as high as in the Sequence V-D. This is accomplished by hardware and operational design, and is demonstrated by analysis of used-oil contaminant levels. The control of sludge deposits by dispersants is essentially a stoichiometric process. The VE test responds very well to increased dispersant treatment in proportion to the increased contaminant load. Chemical analyses of the blowby gases and used VE engine oils offer insight into mechanisms by which engine sludge and wear are generated. Acidic species in the oil appear to play a major role. VE wear also contributes to establishing sludge severity, but this can be avoided by controlling wear with the proper balance of conventional inhibitors. Field test results show that the Sequence VE test correctly ranks the performance of field test oils and discriminates well between good and poor performers.