It has often been said that regular doses of clean, fresh oil provide the least expensive maintenance an owner can give an engine. Textron Lycoming Service Bulletin No. 480 makes these specific recommendations for oil changes under normal operating conditions:
A. Fifty-hour interval oil change and filter replacement for all engines using a full-flow oil filtration system.
B. Twenty-five hour interval oil change and screen cleaning for all engines employing a pressure screen system.
C. Even if the aircraft is flown only a few hours, a total of four months maximum between changes for both systems listed under "A" and "B."