Oil Change Frequency

[Jamie]

Ok, I admit to being a novice on this subject.

My XP-360 manual recommends 50-hour oil+filter changes. I hear about lots of people doing them every 25. What's the skinny here? Are people changing oil every 25 hours just to be anal or what?

[mannanj]

Jamie:

IIRC, there's something in the back of my mind about a three month interval for oil changes regardless of the hours.

I fly about 100 hrs. a year. That is why I change my plane's oil at 25 hrs. and filters at 50.

In my opinion, if you're flying a lot, 50 hr. oil changes would be fine.

[glenn654]

Lycoming says to change at 25 hrs if you have a filter screen, you can go to 50 hrs if you have a spin-on filter or 4 months(I think) time which ever comes first. I always change the oil filter at each change but I am not always able to make the 4 month time limit. At the very least, I change oil and filter twice each year (spring and fall).

P.S.
Mannan, what does "IIRC" mean?

Glenn

[Jeff R]

IIRC, it is If I Remember Correctly.

[Geico266]

Good info above, right on the money.

I'll add get your oil temps get to 200F+ every time you fly to get the moisture out. Open up the dip stick after landing to allow moisture to escape the crankcase. Temps up to 240F are nothing to worry about on climb out. Per Phillips Lubrication Engineer @ SnF "08".

1 gallon of gasolene produces 1.02 gallons of water in an internal combustion engine.

[mannanj]

Glen:

I think it's Teen Speak (Cell Phone messaging) for--- If I Remember Correctly.

[asav8tor]

If you use multi-grade the additives that make it "multi-grade" start to break down and oil consumption can start to go up because by design the engine has big clearances. The oil accumulates combustion by-product waste, lead, water, acid, etc. The longer you go the higher the concentration of that junk. Does it matter 25, 50? Several other variables need to be considered.

Multi or straight wt? (Multi additives breaking down, change oil more often)
Time interval between changes? Oil time, calendar time? (Whichever comes first)
Time interval between flying the engine? week, or weeks? (less frequent fly more frequent change)
Temp and humidity when storing and operating the engine? PHX or humid coastal area? (Dry air good, moist air not as good)
Temp the oil gets during cruise, too hot or too cold? (increase the change frequency as the temp diverges either way from approx 190 for continuous operation, If you drive around at low power looking at 150 deg or push hard and see 240+ all day, change it more)
Use an air/oil separator or inverted oil system? (Increase change interval, both those items return contaminants to the crankcase the engine had tried to expel)

There are more....

[asav8tor]

Originally Posted by Geico266

Good info above, right on the money.

I'll add get your oil temps get to 200F+ every time you fly to get the moisture out. Open up the dip stick after landing to allow moisture to escape the crankcase. Temps up to 240F are nothing to worry about on climb out. Per Phillips Lubrication Engineer @ SnF "08".

1 gallon of gasolene produces 1.02 gallons of water in an internal combustion engine.

If you open the dipstick tube after flying and then turn the prop (not really sure if it's good idea to do that; turning the prop on a hot engine after shutdown) you will be amazed how much water steam will come out even if you got your oil temps up nice and warm during the flight.

[steveKs.]

I fly a Supercub (no filter) and change at least every 25 hours. I plan on the RV8 going 40-50 hours with the spin on.

I could probably forget the hour meter and change the oil by appearance. The oil starts turning a brown-tannish color when I am getting close to the hourly limits. That reminds me to check the hour meter.

[Jamie]

Thanks for all the replies guys. I appreciate the input!