Effects of Extended Oil Changes on Aircraft Piston Engine Wear and Oil Characteristics

Two aircraft reciprocating piston engines were run to their recommended 200 hour overhaul periods utilizing 200 hour oil changes and 100 hour filter changes. The oil was tested each 200 hours for contamination, additive depletion, and wear-metal concentrations. Up-on completion of the study, both engines were disassembled and compared with two engines that were operated 600 hours beyond their recommended 2000 hour overhauls using normal oil and filter change periods. Results indicated that oil could be used safely for 200 hours under closely monitored conditions for a particular aircraft fleet operation.