Question to Paul McBride, the General Aviation News engines expert from Ben Visser, the General Aviation News aviation fuels and lubricants expert: I have had several questions about oil change intervals since I wrote the column, “How often should you change your airplane’s oil?“
One guy said that way back in the past, the oil change interval was a recommended 50 hours or six months. If so, when did it go from six months down to every four months? I believe the answer is that the four months was a result of decreased aircraft usage.
Answer: Ben, I thought you might get some response to the oil change intervals article.
I guess that the guy who said way back in the past the oil change interval was a recommended 50 hours or six months must be a lot older than I am, because to my knowledge, it’s always been four months or 25 or 50 hours depending whether or not the engine was fitted with a full flow filter or not.
I’m not certain that the four-month recommendation came about because of a decrease in aircraft usage, but that recommendation has been around for more than 50 years, even during general aviation’s heydays of the 1960s and 1970s.
I honestly think a lot of people believe the recommended oil change intervals is something the oil companies push in order to sell more oil.
They don’t seem to understand that it’s not the lubricity factor of the oil, but rather the contaminates in the oil that is the concern.
It’s obvious that they’ve never seen the inside of an engine that has had infrequent oil changes and the damage caused by corrosion.
I’d hate to think what some of those engines must look like internally that are still being flown these days that have sat idle for long periods of time with no oil changes and then the owner just starts the plane up and goes flying.
As you probably know, I continue to beat the drum regarding extended periods of inactivity and infrequent oil and filter changes, but there are still many non-believers who someday will pay the price.