My experience with Oil Temps
Lets all agree on a few Standardized conclusions about the oil temps shall we.
1 anytime the oil temp is in the green arc there is no problem
121F to 230F
(lets not debate here about the water needs to boiled out stuff)
2 you can operate in the Yellow arc but not all the time.
231F to 247F. Not all the time could be defined as spending 20 min of a one hour flight is OK
(lets not get to carried away on the debate on this definition on this one)
3 If you operate at the red line of 266F you may cause damage to your Rotax engine per page 2-5 in the Rotax 912 Operating manual. Note the RV12 Dynon 180 is set at 248F, dont know why
4 Although not a continuous problem sometimes on the RV12 we get oil temps above 230F depending on the OAT of the air we fly in and in certain aircraft operating conditions.
In a previous post on a different thread I stated that "I would say that at least 50% of the flying RV12s built have the high oil temps when flying in OATs of 85F or higher." That was my own personal opinion based on discussion on this form going back 2 years. I had received some PM,s about this assumption. However as you can see by this thread that other rv12s are having some problems to.
Today down here in Texas I flew a little different scenario.
Airport elevation 640 feet. Flew race track pattern over airport.
Pressure altitude 1500 feet
Density Altitude 3070 feet
OAT at 1500 feet 88F
RPM 5400
IAS 110 kts
OIl Temp 230 F
EGT normal
CHT normal.
There was no way I could I have climbed at Vx or Vy to 10000 feet with out exceeding the red line of 248F. Looking at John Benders Post and Bob Kibbys post are perfect examples of what we are running into. Here in Texas the standard temp decrease rate doesn't always apply. Meaning 3.5F change per 1000 feet of altitude doesn't always work. Some times in the summer you can see temps in the mid 80s or higher at 4000 feet OAT on the ground can exceed 105F. On my plane once we get through summer the Oil temps run in the green with out any problems. OAT of 85F or lower on the ground and things run fine. Summer only last 3 months anyways. RPM seems to be proportional to Oil Temp in high OAT temp conditions, meaning the higher the RPM the higher the Oil Temp. If I step climb, meaning climb a few thousand feet level off throttle back cool off(oil Temp goes down) then climb again I can manage my temps ok. As you can see in John Benders post that some times OAT can be cooler and you can still encounter the high Oil temps. I'll do some more data gathering for this tread and email to Vans next time I fly.
Reasons why these high temps maybe occurring:
1 Engine break-end may be causing some of the problem.
2 When building the cowl the tunnel maybe not trimmed off enough causing the OIL cooler to be slightly closer to the muffler than Vans two Demonstrators. 1/8 inch could be all it takes.
3 In southern latitudes a slightly bigger Oil cooler maybe required.
4 Or a small change in the cowl design maybe needed.
Time will tell as owners make changes that work.
5 The oil temp sensor could be slightly off on some engines
How I get by:
Step climb to altitude
Throttle back
Fly early in the morning or late in the evening when the OAT is cooler
We maybe just over thinking this problem meaning that these high oil temps may not be that big a deal at all just so long as you don't exceed the Red line!
Conclusion: Some RV12s are having a problem with High Oil Temps. In my opinion sending data to Vans will at least confirm there is a problem. But unless Vans goes into the field and checks rv12s that this is occurring on the fix is far off. I will work within the system though to help out.