A Study of Oil and Filter Change Periods and Engine Oil Monitoring for GM 6V-71 Diesel Bus Engines

Thirteen new 1965 buses having GM 6V-71 diesel engines were put on various oil/filter change periods from 6000/6000 to 25000/25000 miles, and operated in normal passenger service for seven years (1966-1973). Crankcase oil was tested periodically, and oil filters were examined after scheduled removal. Maintenance and operation records were kept. Finally, at the overhaul point some engine parts were examined.

The optimum oil/filter change period was judged to be 25000/12500 miles, in conjunction with field testing for solids load, water and dilution.

Correlations and oil test data, suitable for reference, are given.