FROM 1940 to 1946, 89 heavy-duty diesel-engine lubricating oils were submitted to the Navy for testing. Only 20 were approved on the basis of extensive laboratory and field tests.
Results are reported in terms of a demerit rating system, which covers engine cleanliness, wear, bearing corrosion, and oil stability.
An average weighted cleanliness rating was devised to correlate the relative detergency characteristics of the oils.
The ratings of oils approved each year, the authors say, indicate definite improvements are being made in their detergency characteristics, although they feel that further improvement is both desirable and feasible.