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Oil Change Interval

Piper J3

Piper J3

Well Known Member
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.
 
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
 
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. :D
 
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.
 
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.
 
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.
 
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
 
Harvey rv12 said:
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.
Click to expand...
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.
Click to expand...
 
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.
 
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?

 
Todenhal,

Are you using Decalin when you add AVGAS? I see my oil turn brown at 50 hrs when I use unleaded car gas, and using Decalin for the rare AVGAS fill up seems to yield the same result.

Rich
 
25 hours if you run on leaded fuel. 50 if you run on 91/93 premium auto fuel. It is written.

I run only auto fuel, and plan to change the oi at 25, oil and filter at 50.
 
Having started this thread yesterday I appreciate everyone?s input. I guess I?m not the only one searching for advice on this subject. I?ve weighed all the comments and decided that I?ll change oil at 50 hours and filter at 100 hours. Oil looks clean but I bet when I drain it I?ll find a deeper amber color.

I love the RV-12 with 912ULS. Operation is extremely simple and straightforward. On two separate days I flew takeoff and landings with a passenger. On both days the Hobbs = 1.9 hours and fuel burn for each day was 6 gallons measured with calibrated dipstick. Two 200 pounders and ? fuel gives over 1000 fpm climb at 60F 1000 ASL. Van?s did an excellent job on this design.
 
RFSchaller said:
Todenhal,

Are you using Decalin when you add AVGAS? I see my oil turn brown at 50 hrs when I use unleaded car gas, and using Decalin for the rare AVGAS fill up seems to yield the same result.

Rich
Click to expand...

Hey Rich, I do carry a small bottle of Decalin, but on this trip, I only needed to put in 10 gal of 100LL, and I didn't think it was necessary for that small amount. This was the only time that 100 LL was used in my 12, and the Decalin bottle remains full. I would have expected adding Decalin would make the oil more prone to getting black, due to the lead scavenging properties of the oil. Perhaps I was wrong...........Tom
 
Right From the Rotax Maint Manual - Edition 2 - Revision 0

Section 05-20-00
Page 16, Paragraph 14 Oil Change

Oil and filter change at 50 hours unless 100LL is used more that 30% of the time. Then it is 25 hours.
 
edition 3, rev 2, feb 01, 2015
every 50 hrs if you use avgas, 100hrs if you use unleaded fuel.

maybe it was different in the older manual, but this is from the most current manual.
 
todehnal said:
Right From the Rotax Maint Manual - Edition 2 - Revision 0

Section 05-20-00
Page 16, Paragraph 14 Oil Change

Oil and filter change at 50 hours unless 100LL is used more that 30% of the time. Then it is 25 hours.
Click to expand...

Ahhh, OK, I see where at least some of the confusion lies: Edition 3, Rev 1 of the Maintenance Manual, which I think is the latest except for some change pages unrelated to this, gives 100 & 50 hrs respectively, if I'm understanding it correctly, rather than 50/25 (http://www.vansairforce.com/community/showpost.php?p=1073892&postcount=10). Looks like they've changed their recommendation.

Changing oil & filter sooner can never hurt, I was just having trouble reconciling the discussion with the Rotax documentation
 
tomkk said:
Ahhh, OK, I see where at least some of the confusion lies: Edition 3, Rev 1 of the Maintenance Manual, which I think is the latest except for some change pages unrelated to this, gives 100 & 50 hrs respectively, if I'm understanding it correctly, rather than 50/25 (http://www.vansairforce.com/community/showpost.php?p=1073892&postcount=10). Looks like they've changed their recommendation.

Changing oil & filter sooner can never hurt, I was just having trouble reconciling the discussion with the Rotax documentation
Click to expand...

What actually causes the confusion is that the 100 hr / 50 hr in the Line Maint. Man. are the required intervals.
In the recommended fluids Service Instruction ( don't remember the # right now) the recommended intervals are 50 hr and 25 hr.
 
rvbuilder2002 said:
What actually causes the confusion is that the 100 hr / 50 hr in the Line Maint. Man. are the required intervals.
In the recommended fluids Service Instruction ( don't remember the # right now) the recommended intervals are 50 hr and 25 hr.
Click to expand...

Oh, interesting, thanks, I missed that. Have to chase that one down.
 
rvbuilder2002 and tom,

SI-912-016R8 paragraph 3.3 (link below) does suggest 25 hour intervals with the use of leaded fuel. I don't remember ever seeing it written that 50 hour intervals should be followed with mogas. Even so, It's a good idea to follow a 25 or 50 hour interval, depending on fuel of course.

I've serviced at least 50 gearboxes and the lead build up can get pretty nasty causing issues with parts wearing prematurely, expensive parts.


http://docusearch.flyrotax.com/files/pdf/d06038.pdf
 
I’m just back from AirVenture with lots of info and COVID! I spent time at Rotax looking at their new engines and spoke to their rep regarding oil change intervals. He showed me online in the maintenance manual(912ULS) suggested service intervals: Mogas only, 100 hours oil and filter. And they now recommend their own oil blend($20/liter). F/W/I/W.
 
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