Evaluation of Dispersancy by Analytical Methods

Test severity, inhibition and oil discrepancy: these are factors which influence the formation of sludge and the extent of its settling in the engine.

By appropriate used-oil analyses it is possible to calculate indices of the oil's performance which are largely independent of the type of engine used and the test procedure followed. The ASTM D 893 test procedure is inapplicable to a large number of modern motor oils.

An alternative method based on the filtration of used oils over membrane filters has been of great help in recent years. However, a newly developed photometric method seems promising in overcoming most present analytical difficulties.

The indices obtained from used-oil analyses can become the only feasible test method in the development of long drain oils.