Oil Temperature

I now have 110 hours and counting on my 912 powered RV-12, and things have gone very well so far. If I had the opportunity to get one improvement in performance numbers, it would be a bit cooler oil temp. I know, the Rotax operators manual states that normal range is 190 to 230, but on a hot day, when I exceed 220 in a climb, I start getting nervous, start flattening out the climb, and easing back on the power. I've seen that in as little as after a 5, or 6 minute climb. That just seems so tough on the oil, even if the engine can handle it. I'm use to seeing these numbers under 200 on lycs and conts. Max is stated at 266. I can't even imagine that!! I have Bill's cowl mod, and my concerns may be unfounded, so, I thought that some summer day climb oil temp numbers might be nice to share. I'm using Shell Sport oil, and have considered moving to a motorcycle oil in hopes that it may have a higher temperature formula. Kentucky summers get pretty toasty, but with our good cabin airflow, and the addition of a sunshade, creature comforts in the RV-12 are pretty good even on mid 90's days. My cruise oil temp will run right at 200, or slightly above, which I guess is okay. Any experience and comments will be greatly appreciated.................Tom

Hi Tom,
Up to 230F is not an issue. Normal, depending on the time of year and your geographic location can be anywhere from 200F-230F. I know several owners running 220F-225F with OAT's at 90F-95F.
On a warm day of 90F-100F you may have temps running around 220F-230F in cruise. This isn't abnormal. Temps at 231F start the yellow zone for temps and in a climb you may see 230F-240F and I wouldn't panic over that if the temps come back when in cruise. The yellow warning area of 230F just means it is a climbing temp and you need to keep an eye on it. It doesn't mean it is causing any damage or issues. The other things that affect oil temp for the average person is prop pitch and throttle position. The temps can vary at times depending on the throttle postion as this will increase and decrease fuel which may increase and decrease temps. Too much prop pitch will increase temps too. You should get a minimum of 5500 rpm at WOT in level flight.
The Aero Shell Sport Plus 4 oil was reformulated over the last 4 years and just came out with a final formula this year for public use. It can easily handle your engine temps. It was specifically formulated to handle a high wear and temp engine and it was tested with high time flight schools over thousands of hours. As a side note: Right now Rotax is looking at Mobile One for a possible issue, but nothing has come out yet and this is all I know.


" I'm using Shell Sport oil, and have considered moving to a motorcycle oil ".

For the most part it is a motorcycle oil with its properties.

You don't want an oil too cold as it will not burn off any impurities. I have heard from several RV12 owners and their temps. Yours is just like theirs, normal in hot weather.

Thanks Joe. It's nice to know that I'm running with the group on oil temp. I'll remain in climb a bit longer on the next hot day flight, monitor it closely, and see if the temp settles down.........Tom

The ROTAX manual says 285F is the max. Recently I hit about 255F with an OAT of 115F and 50 lbs below gross. I made a precautionary landing and let the engine cool down on the ground.

I got my oil T limits from page 2-2 of the Ops Manual.

You guys need to relax a little about oil temps. This isn't a Lyc or Cont and you can't compare it to them. 200-230 is a normal operating temp for this engine and you can run it all day like that. And while you want to watch higher temps in climbs it's hard to avoid 230-240 on hot days.

I live in the Sacramento area where we have many days over 100 and while I only have about 50 hours on my RV-12, I have near 1100 on the 912 ULS in my Rans S-7S. It's required no more than routine maintenance and run at those temps for 8 years.

I've used Mobil Racing 4-T for 1000 hours but have recently switch to Shell Sport Plus 4 just to try it out. Use less than 1/2 quart btw 100 hour oil changes. We were taught in Rotax maint. school that running low oil temps, low rpm, and 100 avgas were all considered severe duty and required increased maint.

Bill

Hi RFSchaller,

I tell people that the manuals are written for 3 engines. The 912 A, F, UL and the 912S / ULS and the 914.

When you read the manuals make sure you read the correct pages for your engine application.

The 285F temp on pg. 2-2 of the Operations manual is for the 912 A, F and UL.

The max temp on pg. 2-5 is 266F for the 912 S/ULS.

If you run temps on the 912ULS over 250F+ I would be concerned and want to find a way to bring this down. There are ways.

Joe,

Thanks for pointing out my error. The hi temps were the result of the extreme OAT and climbing near max gross weight. Nice to know I was still below the max temp.

Rich

bajapilot said:

You guys need to relax a little about oil temps. This isn't a Lyc or Cont and you can't compare it to them. 200-230 is a normal operating temp for this engine and you can run it all day like that. And while you want to watch higher temps in climbs it's hard to avoid 230-240 on hot days.

I live in the Sacramento area where we have many days over 100 and while I only have about 50 hours on my RV-12, I have near 1100 on the 912 ULS in my Rans S-7S. It's required no more than routine maintenance and run at those temps for 8 years.

I've used Mobil Racing 4-T for 1000 hours but have recently switch to Shell Sport Plus 4 just to try it out. Use less than 1/2 quart btw 100 hour oil changes. We were taught in Rotax maint. school that running low oil temps, low rpm, and 100 avgas were all considered severe duty and required increased maint.

Bill

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Thanks Bill. This is what I was looking for. I will be much more relaxed as the oil temp climbs above the mid 220s, or even up to 240. I can't imagine mine going much higher than that, from what I have experienced in our Kentucky summers. I just needed to hear from others who have been there.............Tom

Tom, did you move the oil cooler forward? I performed the mod on RV12#2 and have not seen temps in the yellow at all so far under any condition. It looks like the new exhaust pipes will solve the problem also.

Bahapilot, check your pm's

It's interesting that Scott said relocating the muffler only gave a 7F improvement in oil Temp. Sometimes I entertain the idea of water spray like they use at Reno. At least it would be a solution for climbs in PHX during August!

New RV-12 mod in the works?

RFSchaller said:

Sometimes I entertain the idea of water spray like they use at Reno. At least it would be a solution for climbs in PHX during August!

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"RV-12 contrails" (instead of smoke...lowers oil temps and eco friendly too!)

Al Gore would approve!

Dave12 said:

Tom, did you move the oil cooler forward? I performed the mod on RV12#2 and have not seen temps in the yellow at all so far under any condition. It looks like the new exhaust pipes will solve the problem also.

Bahapilot, check your pm's

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Hey Dave, I do have your cowl mod. I misspoke in my original post when I said Bill's cowl mod. It definitely is yours. Thanks, so much. That really did help a lot, and I have never seen temps in the yellow. I am much too watchful to allow that to happen. From seeing the posts here, I have been a bit too cautious, and I plan to raise my personal oil temp max closer to book numbers. I guess, as long as I never see the oil temp in the yellow, I will consider it good. Thanks again for sending me the details on your cowl mod. That certainly made the job a lot easier..........Tom

RFSchaller said:

It's interesting that Scott said relocating the muffler only gave a 7F improvement in oil Temp. Sometimes I entertain the idea of water spray like they use at Reno. At least it would be a solution for climbs in PHX during August!

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What would really be interesting would be to know if the relocated muffler also lowered the temps in other areas within the cowl, such as the areas by the carbs, and the firewall shelf, where the voltage regulator was originally installed??? Lowering the muffler could reduce fuel temp, and have other multiple advantages, as well..............Tom

FWIW Last summer I was running high oil temps with ambient temperatures in the 80's on climb out. I considered moving the oil cooler but since my prop pitch was more cruise than climb (about 4850 rpm) I decided to change the prop pitch first. By changing the pitch to get about 5200 rpm on climb out my oil temps have stayed below 230 this summer. The trade off of a lower cruise speed and lower fuel consumption was worth it.