Oil Change Interval

[Piper J3]

I have looked at the Rotax maintenance manual and read thru the VAF threads and can?t settle on an oil change interval. I changed oil at 50 hrs TT and I?m now approaching 100 hrs TT. Oil used is Mobil 4T 10W-40. I have only added a thimble full of oil in 44 hrs and oil still looks pretty clean. I use E10 93 octane auto fuel exclusively. Starting with the next oil change I will begin using Aeroshell Sport Plus 4. No real reason for changing to Aeroshell other than Rotax recommendation.

I have seen oil change recommendations for 50 hrs up to 100 hrs when running auto fuel. I?m thinking about extending this oil change to 75 hours. What complicates matters is oil temps in winter flying may not have baked out moisture from combustion. Flying now in warmer temps I suspect all the moisture has been baked out so should be hunky-dory. I may install a shutter for the oil cooler for next winter ? still to be determined.

Any comments welcome.

[Ex Bonanza Bucko]

If you use Avgas....100LL.....Rotax says you should use the Shell Sport Plus 4 because it's half synthetic and half dinosaurs.....full synthetic apparently does not scavenge lead like the dinosaur stuff.

I have an SLSA from Van's and I change oil at 25 hours and the filter at 50 because I use Avgas.....if I'm on a trio I go to 50 hours.

EBB

[turbo]

thats right, avgas = 25 hour changes. the problem is the lead build up getting in the gear box. do the right thing. oil is cheap.

[DaleB]

I think we all agree that 25 hours is the correct answer when running avgas. But the answer with unleaded doesn't seem to be as clear. I finally dug through the line maintenance manual long enough to find the maintenance schedule. There, buried a few pages in, was the oil change schedule.

50 hours, oil and filter both. 200 hours to check and clean the oil tank.

[AZLeeJay]

I agree that there is confusion regarding the interval, I'm erring on the conservative side and changing every 50hrs as long as I'm using less than 30% 100LL.
Plus it gives me a good reason to pull the cowl and have a good look around.

[Harvey rv12]

If I read the maint manual correctly, it says change oil at 50hrs if you use more than 30% avgas, but 100hrs if you use unleaded gas.
100hrs in a RV-12 equates to about 8000 10000 mi in an automobile. that is the suggested frequency for many new cars, but I find that to be a little long for my tastes. 50 hrs is a reasonable number.
last few changes I did were about $75 each time. 3qts @ $12 ea, filter about $24, tax & shipping = $15. so it is not cheap, but well worth the effort.

[todehnal]

I decided to go with the AeroShell Sport 4 and adopt the 50 hr. regiment since I use 93 octane alcohol free exclusively. I have been ecstatic with the color, and feel of it, even after 50 hrs. Last fall we made a trip that required me to buy a tank of 100LL. At about 27 hrs. I was not happy with the color or texture of the oil and changed it early. I couldn't believe the blackness of the oil with just one tank of 100LL. Now, with almost 25 hrs. on this oil change, and exclusively using ethanol free 93 auto fuel, I'm pleased to see a nice light amber color to my oil again. For me, 50 hrs. works out great, as long as I stay away from 100LL..........Tom

[DaleB]

Originally Posted by Harvey rv12

If I read the maint manual correctly, it says change oil at 50hrs if you use more than 30% avgas, but 100hrs if you use unleaded gas.

I've heard that, but haven't found any documentation to back it up. I'd love it if that were true, but I think it's actually half that. Do you have a reference for the 100 hour interval?

What I found was a 50 hour interval specified in the Line Maintenance Manual Edition 3 / REV 2, chapter ref. 05-20-00 P.16. I'm sure the interval recommended for running avgas is 25 hours, per Rotax SI-912-016R8:

If operating with leaded AVGAS fuel, we recommend a change of engine oil every 25 operating hours.

[Sink]

25 hr. oil change intervals for 100LL is indeed in writing and should be followed. Don't use 50 hr. for 100LL or after a few hundred hours you may wish you hadn't.

We highly recommend oil changes with unleaded auto fuel at 50 hrs. even though the manual allows more. This has been taught this way as far back as I can remember. Oil changes are cheap enough and I never saw a reason why people want to go to 100 hr. changes.

[tomkk]

Not trying to be argumentative, just trying to reconcile the discussion with the Rotax Maintenance Manual where I think it says oil change every 100 hrs unless more than 30% is leaded fuel, in which case it's 50 hrs. I don't remember seeing anything about 50/25 hour intervals. Did I misunderstand Rotax's manual?