High Oil Temps (again)

pauldan181 · #1 06-02-2009, 03:28 PM

Now that the weather is hot I'm seeing my oil temps creep over 200 again in cruise. My 8A was born and raised in Minnesota and I only had to deal with oil temps over 200 a couple of days per year. I'm in North Carolina now and would like to see a few degrees cooler stabilized oil temps.

I'm due an oil change and wondering if anybody has seen any temperature drop from changing to a semi-synthetic like Exxon Elite. I'm using Phillips 20w50 now.

Thanks

Paul Danclovic
Jamestown NC
RV-8A N181SB

yakdriver · #2 06-02-2009, 03:46 PM

How much over 200 do they creep? I wouldn't worry about anything under 215. Don

RV10inOz · #3 06-02-2009, 08:45 PM

Agreed!

Ohhh and some more words to get over the min character count

Geico266 · #4 06-02-2009, 08:57 PM

Quote:

Originally Posted by yakdriver

How much over 200 do they creep? I wouldn't worry about anything under 215. Don

Anything under 230 is fine, 240 and you need to figure it out.

Kyle Boatright · #5 06-02-2009, 09:37 PM

Quote:

Originally Posted by pauldan181

Now that the weather is hot I'm seeing my oil temps creep over 200 again in cruise. My 8A was born and raised in Minnesota and I only had to deal with oil temps over 200 a couple of days per year. I'm in North Carolina now and would like to see a few degrees cooler stabilized oil temps.

I'm due an oil change and wondering if anybody has seen any temperature drop from changing to a semi-synthetic like Exxon Elite. I'm using Phillips 20w50 now.

Thanks

Paul Danclovic
Jamestown NC
RV-8A N181SB

What are your actual temps and what is the OAT at the surface when you see those temps?

I chased oil temperatures for about the first year I flew my RV-6. I made numerous minor modifications until I found one that worked (bigger baffle opening for air into the cooler), and talked to a bunch of experts - Lycoming, Van's, Pacific Oil Coolers, Skyranch Engineering, Don George, etc. Based on data from those sources, the ideal oil temperature is ~190 +/- 10F. But you're likely to have a hard time maintaining that on a 90 or 100F day.

My experience was that switching to a semi-synthetic didn't move my oil temperatures enough to notice. In theory, there should be slightly less friction when running the semi-synthetics, but friction is a very small component of the heat generated by a Lycoming.

My $0.02 worth is that if you're seeing temperatures of slightly greater than 200F on >85F days, no immediate action is needed. If you see temps >215 during cruise, you're getting to a point where it is probably time to try and bring the temps down.

Kyle Boatright · #6 06-02-2009, 09:39 PM

Quote:

Originally Posted by pauldan181

Now that the weather is hot I'm seeing my oil temps creep over 200 again in cruise. My 8A was born and raised in Minnesota and I only had to deal with oil temps over 200 a couple of days per year. I'm in North Carolina now and would like to see a few degrees cooler stabilized oil temps.

I'm due an oil change and wondering if anybody has seen any temperature drop from changing to a semi-synthetic like Exxon Elite. I'm using Phillips 20w50 now.

Thanks

Paul Danclovic
Jamestown NC
RV-8A N181SB

What are your actual temps and what is the OAT at the surface when you see those temps?

I chased oil temperatures for about the first year I flew my RV-6. I made numerous minor modifications until I found one that worked (bigger baffle opening for air into the cooler), and talked to a bunch of experts - Lycoming, Van's, Pacific Oil Coolers, Skyranch Engineering, Don George, etc. Based on data from those sources, the ideal oil temperature is ~190 +/- 10F. But you're likely to have a hard time maintaining that on a 90 or 100F day.

My experience was that switching to a semi-synthetic didn't move my oil temperatures enough to notice. In theory, there should be slightly less friction when running the semi-synthetics, but friction is a very small component of the heat generated by a Lycoming.

My $0.02 worth is that if you're seeing temperatures of slightly greater than 200F on >85F days, no immediate action is needed. If you see temps >215 during cruise, you're getting to a point where it is probably time to try and bring the temps down.

A couple of suggestions would be cylinder blockers to reduce the cooling air consumed if cylinders on #1 or #2 are cooler than #3 and #4. Also, if your cooler is baffle mounted, a slight increase in the size of the baffle opening might be beneficial. It was for me.

pauldan181 · #7 06-03-2009, 05:38 AM

Thanks for all the responses guys. I didn't include any specific temps in my original question as I had not really wanted to get into a discussion about what temps were OK or not. There's plenty of that archived around here.

My oil temps are higher now for two reasons, the change to a warmer climate, and I'm leaning a little closer to peak EGT than before, If I only lean to 100 ROP, my temps stay below 200. Go figure.

If 180 to 190 deg. oil temp is hot enough, any hotter may be fine but certainly isn't doing any good either. If I could loose 5 degress by spending a buck a quart more for oil I'll do it. More than anything I guess I just wanted to experiment a little. We all like to experiment with our planes, right?

Paul Danclovic
Jamestown NC
RV-8A N181SB

yakdriver · #8 06-03-2009, 06:28 AM

Is your engine fuel injected or carb, four probe egt/cht or single point? What are your cylinder head temps doing when leaned "close to peak". What is close to peak, 50 ROP,25 ROP? Again if your oil is staying right around 200 on an 85 degree day you have no problem. If you are running a carb with single probe egt 25degrees ROP you are inviting detonation or at the minimum higher cylinder head temps that increase oil temps. Don

David-aviator · #9 06-03-2009, 06:41 AM

I flew 1.7 hours the day before yesterday with the OAT at 89F which included some full power runs and local stuff going to 3 air ports. Oil temp got up to 180 max with CHT finally breaking 400 (405 was the number on 2 cylinders, the other 2 less than 400) on the last take off - with a much heat soaked engine. (CHT backed off to 385 quick after level at 4500')

IMHO, if you want good oil cooling (which will also affect CHT), go with a SW-8432R cooler and mount it ala the RV-10 on the firewall with 4" scat tubing.

Geico266 · #10 06-03-2009, 07:00 AM

Paul, another "fix" I have used for getting cooler oil temps in hot weather is to add a removable "extention" to the bottom of the coweling. I take a piece of .025 skin approximately 18" (measure the bottom of your coweling opening) x 6" and bend it 30 degrees towards the ground (in the middle of the 6"). Basically, you are adding an airflow "trip" to increase the amount of negative air pressure under the coweling. Several spam cans use this method for increasing coweling airflow, and some have an "in flight" adjustment handle.

I used the existing holes and duct tape to try it and it reduced the oil temps by 5-10 degrees by just increasing coweling airflow . After I tried it and found it worked I removed the duct tape and added screws. I add it in the summer months to cool the IO-540 on the RV-10 and I have added it to a 0-360 RV-9a and it worked also.

If you are interested I can get a picture of it.