Field and laboratory experiences with extended oil drain intervals in diesel truck engines

Field and laboratory experiences with extended oil drain intervals in diesel truck engines in a program initiated in 1970 indicated that drain intervals of 30,000-40,000 km provide the best cost-risk relationship for the Canadian environment; the life of a good oil filter is about 40,000 km max. High total acid number appeared to correlate with wear. The evaluation involved determination of engine wear and condition, oil consumption and viscosity, total base and acid numbers, and content of insolubles, iron, copper, lead, and silicon in four SAE 30, two 10W/30, and 315W/40 oils used in three truck engines at three sites after 320,000-350,000 km with oil drain intervals of 13,000-160,000 km or no drain. Of 44 oil samples from four line-haul trucks and 72 used oil samples from trucks used in a gravel quarry and cement operation, 52 and 15Vertical Bar3<, respectively, were taken after 28,000 km and 250 hr drain periods, respectively, and were unsatisfactory for further use, mostly due to contamination by wear particles or abrasives. Mixing a 15W/40 oil used for 80,000 km with new oil in the CLR L-38 and Petter AVB laboratory test engines gave generally satisfactory results.