How Often Should You Change Aircraft Engine Oil?

Send us questions by commenting below or emailing John & Jeff at: [email protected] Often Should You Change Aircraft Engine Oil?The 50-hour aircraft engine oil change interval in your POH was written for flight schools flying constantly — not for the owner who flies a few hours a month and parks the plane. John and Jeff break down what the book actually says and what most owners miss.Aircraft engine oil isn't automotive oil. It's only about 6 to 7% additives compared to 13 to 16% in conventional auto oil, and those additives — the ones fighting moisture, acids, sludge, and carbon — start breaking down around 20 to 25 hours. After that, the oil still lubricates, but it's no longer protecting the inside of your engine from the corrosion cycle that runs every time the crankcase heats up and cools down. That's how camshaft and lifter pitting starts on Lycomings, and it's why John and Jeff see rust inside engines from owners who swear they fly regularly.The piece almost everyone overlooks is the calendar rule: change the oil every four months regardless of hours. Two hours on the engine in four months still means it's time. The hosts walk through why "regular use" isn't ten hours in one trip followed by three weeks parked, why active preservation only happens in the air at temperature, and why the difference between a 30-hour and 50-hour oil change is one extra change per 100 hours — cheap insurance against an engine teardown.In this episode, we cover:- Why the 50-hour interval was written for flight schools, not typical owners- The 4-month calendar rule in the POH and what it actually requires- How aircraft oil additives break down by 20 to 25 hours- Why aircraft oil is only 6 to 7% additives versus 13 to 16% in automotive oil- How condensation, acids, and the crankcase greenhouse effect cause internal rust- Why camshaft and lifter pitting hits both Lycoming and Continental engines- Why ground runs and taxiing don't count as active preservation- The 30 to 35 hour oil change recommendation and pulling the filter every 100If you fly less than 200 hours a year, this episode helps you stop a corrosion problem before it turns into a top overhaul.TIMECODES00:00 What the POH 4-month oil change rule actually says00:30 Is the 50-hour oil change interval right for your flying?01:33 Why aircraft oil only has 6 to 7% additives02:42 How rust starts inside engines that "fly regularly"04:18 Why 30-35 hour oil changes are cheap insurance05:16 What "regular use" really means for piston engines06:22 Humidity, condensation, and the crankcase greenhouse07:16 Camshaft and lifter pitting on Lycoming vs Continental08:11 Final recommendation: 30-35 hours, every third change pull the filterGet in touch!Web - SignatureEngines.comEmail - [email protected] - youtube.com/@SignatureEnginesInc