First Thread! Oil Temp and winterization

[Ragsf15e]

Awesome! I just got a new 252/Encore conversion and now we have our own K model thread!  I’ve had mine for about a month and flew it from Tennessee to Washington State in January to bring it home!  Really lucked out with the weather and it was clear the whole way!

Im still getting use to it, but mostly running it at 65% power lean of peak and she seems really fast!

One question I’ve had is about my oil temp.  Has anyone with a K used a winterization cover over the cooler (or tape)?  My engine runs very cool (the oat has been cold for sure but not Canada cold) and the oil temp doesn’t show more than ~125.  Chts are upper 200s.  @kortopates suggested it’s likely an indication issue - probe or wiring which I agree with.  However, I was wondering if anyone has used the winterization stuff though and what change they saw? Today I cruised at 10k, 65%, -10c and saw oil temp of 110 which seems impossible.  It also seems like the probe is directly behind the oil cooler and difficult to access.

 

[Fix]

I asked the moderators if they could give us an late Christmas present with our own M20K specific forum.
Hope it will be filled with lots of useful information for M20K owners.

[Fix]

I also have low indicated oil temps, and also got the advice from Paul to check the probe/ground at instruments since he claims it's a common issue with low indicated oil temps on M20K.

Just left my M20K for my first annual, and we'll see if we can find a good way to see if my probe is reading correctly or what else it could be.
Before I start to use aluminium tape on the Oil Cooler.

I also looked at some Youtube videos of M20K 252 that had low oil temps.
Will check if they just started up the engine, or if they were cruising for longer period.

I have the stock analog gauges installed.

[Z W]

My oil temp also reads low, usually in the 140's. I've never blocked the oil cooler. When it's very cold outside, I run with the cowl flaps fully closed which helps keep the oil temp up.

I read somewhere on here that if it's indicating 140 at the probe, it's still likely hot enough to vaporize moisture elsewhere in the engine, so not to worry. But I'm just repeating something I read on the internet there.

You're running a lower power setting than I usually do - I go closer to 75%. Nothing wrong with your setting but you might try running more power for a while and see what it does to your oil temp. I think I'd be concerned at 109 degrees. The turbocharger needs 100 degrees minimum to function properly, according to its documentation, and you may be getting too close to that.

[Pinecone]

3 hours ago, Fix said:

I asked the moderators if they could give us an late Christmas present with our own M20K specific forum.
Hope it will be filled with lots of useful information for M20K owners.

Except the title says 231 only.  So we 252 owners (and Encore) are not welcome it seems.

 

[Pinecone]

109 is a bit low.  I see 140 - 150 normally.

[jrwilson]

I have a 231 with low oil temps, 150-160 in the winter.  I have started using a winterization plan with some aluminum tape on the oil cooler.  It brings the oil up to about 170.

[Falcon Man]

I have an aluminum plate that covers 50% of the oil cooler that I have used in the winter and the temp gets to 180 on my JPI EDM-900. This has worked well on my 252, 262 and Encore.

[Fix]

5 hours ago, Falcon Man said:

I have an aluminum plate that covers 50% of the oil cooler that I have used in the winter and the temp gets to 180 on my JPI EDM-900. This has worked well on my 252, 262 and Encore.

Before I cover oil cooler to get higher temps, I want to make sure that I have correct reading on my oil temp gauge.

Sure I fly with 62-65% LOP but I expect higher oil temp.

CHT and Oil pressure is all good.

[Z W]

9 hours ago, Falcon Man said:

I have an aluminum plate that covers 50% of the oil cooler that I have used in the winter and the temp gets to 180 on my JPI EDM-900. This has worked well on my 252, 262 and Encore.

How does it attach to the oil cooler? Do you tape it in place? A picture would be great if you have one.

[Falcon Man]

Here is a picture. I powder coated it for durability.

IMG_0086.pdf

[Steve Dawson]

I have a cover that I put over mine during the winter and get 180-190 f. Hopefully the internal engine temps will be above the boiling point to try and stop any condensation created. 

[N201MKTurbo]

5 minutes ago, Steve Dawson said:

I have a cover that I put over mine during the winter and get 180-190 f. Hopefully the internal engine temps will be above the boiling point to try and stop any condensation created. 

You don't have ro get it to boiling to drive out the water. The vapor pressure of the water increases with temperature. Boiling is just the temperature where the vapor pressure exceeds the ambient pressure above the liquid. Even if it is 10 degrees below boiling, it is vaporizing the water. And if you are at 10000 feet, the boiling point is at 193.6 F.

[Ragsf15e]

5 hours ago, Falcon Man said:

Here is a picture. I powder coated it for durability.

IMG_0086.pdf 615.58 kB · 9 downloads

That’s a great visual, thank you!

[Steve Dawson]

On 2/21/2025 at 8:29 PM, N201MKTurbo said:

You don't have ro get it to boiling to drive out the water. The vapor pressure of the water increases with temperature. Boiling is just the temperature where the vapor pressure exceeds the ambient pressure above the liquid. Even if it is 10 degrees below boiling, it is vaporizing the water. And if you are at 10000 feet, the boiling point is at 193.6 F.

I’m going to stick with my reasoning. Oil is thicker than water and even though it may evaporate some of the water out of the oil, the water will rise to the top of the crankcase oil after sitting and then through the internal engine causing corrosion. Not getting high enough temperatures will only add to the moisture within the engine causing more issues. Run the engine above 180 and for longer durations than an hour at a time to help get rid of the water. Lycomings have this issue with their camshafts rusting.  

[N201MKTurbo]

5 minutes ago, Steve Dawson said:

I’m going to stick with my reasoning. Oil is thicker than water and even though it may evaporate some of the water out of the oil, the water will rise to the top of the crankcase oil after sitting and then through the internal engine causing corrosion. Not getting high enough temperatures will only add to the moisture within the engine causing more issues. Run the engine above 180 and for longer durations than an hour at a time to help get rid of the water. Lycomings have this issue with their camshafts rusting.  

Oil should float on water. If any water comes out of suspension, it should go to the bottom of the crankcase. The specific gravity of motor oil ranges from 0.86 to 0.96.

[Steve Dawson]

1 hour ago, N201MKTurbo said:

Oil should float on water. If any water comes out of suspension, it should go to the bottom of the crankcase. The specific gravity of motor oil ranges from 0.86 to 0.96.

So you want the water to stay in the oil pan and accumulate? Does it just sit and stay in the bottom of your engines? 

[N201MKTurbo]

1 hour ago, Steve Dawson said:

So you want the water to stay in the oil pan and accumulate? Does it just sit and stay in the bottom of your engines? 

What I want has nothing to do with it. For the mast part any moisture in the crankcase is in suspension in the oil or condenses on the inside after the engine cools.

[Steve Dawson]

It suspends, but you just said their specific gravity is different? 

[Pinecone]

Some is suspended in the oil.  Some will condense on surfaces and run down and be liquid water in the bottom of the sump.

Running hot enough and long enough will remove the liquid water and much of the suspended water.  But the same time you are removing suspended water due to heat, you are whipping the oil with moist air, putting suspended water back in.

 

[jlunseth]

I live in Minnesota where we see some truly impressive cold temps on a routine basis. Every year, at the start of the winter, I have my A&P install an oil cooler block. It is just some blocks of foam taped together that fits in the oil cooler. In the K's the OT must remain above 100 dF. This is in the POH. The issue is that if the oil gets too viscous it fails to pass through the very thin bearing space of the turbo, where it provides both cooling and lubrication. You don't want your turbo to go without oil. I have often run with the OT down to 100 dF without incident, but for me it becomes a real concern on super cold days if the OT want to be colder than that. I don't see any problem with 125 or 150, I ran the old engine there quite a bit in the winter and it went several hundred hours over TBO and the turbo went several hundred hours past the 1,000 mark. After 1,000 hours I had the turbo borescoped very annual just to be sure and there were no problems. But use your own best judgment.

There was just a thread in one of the other forums on cold weather ops. One other thing to note is that if it is really cold, say anything below 15 dF, it is important to spend time on the ground running your checklists and letting the engine warm the engine compartment. There are some non-engine-attached components in there that need to be above freezing, notably the air/oil separator. If it freezes it blocks the breather with the result that the compression in the running engine causes the oil to exit through every available orifice. You can get remarkable oil streaks as wide as 18" down the sides of the full length of the aircraft. I am sure the brake master cylinder would appreciate a little heat also.

Edited March 16 by jlunseth