Laboratory evaluation of the dispersancy power of a gasoline engine oil and its relationship with sequence VE test results

The evaluation of the dispersancy power of a gasoline engine oil is included among such international specifications as those of the Committee of Common Market Automobile Constructors (CCMC) and the American Petroleum Institute (API). Such an evaluation is carried out by means of long, severe, and expensive engine bench tests, the engines used being Mercedes M102E (CCMC G4 and G5 levels) or the Ford Pinto 2.3 (API SG and SH levels). The cost of these tests necessitates pre-selection of oils by laboratory tests and these need to be a reliable indicator of bench test performance. The present study proposes two new laboratory methods, the OXYDISP and the POTDISP tests, which associate artificial ageing of the lubricants with modified blotter spots tests. These tests showed excellent correlation with Sequence VE engine test results. They were also capable of distinguishing oils of different API standards. They therefore provide an effective tool for preselection of lubricants, without pretending to be a replacement of or substitute for Sequence VE or other engine bench tests.