oil temps

[a64pilot]

Some of you may know I've been chasing a high oil temp problem. I know it's not blow-by, oil cooler, vernatherm, baffling. Addition of the Maule "cooling lip" hasn't helped.
It's been suggested that I'm chasing my tail, or put another way, you can't fix something that's not broken.
On hot days how high of an oil temp do you run? I'm an IO-540W1A5D and will see over 200 and as high as 210 in cruise when OAT is close to 100.
Does anybody else see this high of a temp? How high?

[Green Hornet]

Some of you may know I've been chasing a high oil temp problem. I know it's not blow-by, oil cooler, vernatherm, baffling. Addition of the Maule "cooling lip" hasn't helped.
It's been suggested that I'm chasing my tail, or put another way, you can't fix something that's not broken.
On hot days how high of an oil temp do you run? I'm an IO-540W1A5D and will see over 200 and as high as 210 in cruise when OAT is close to 100.
Does anybody else see this high of a temp? How high?

I have seen oil temps hotter than 235 or higher on stock gauge. I also have a IO-540W1A5D.
This was in August in Texas, NM, AZ. where OAT was 90F to a 100F. After installing an EI there was an average of 40 to 50 degrees difference in CYL Head temp in CA where OAT is cooler by 25 degrees. CA is now avg 50 to 70F degrees OAT. Next time I am in 100 degree temp I will make a note of numbers but I think these engines run hot in hot weather.

[Ernie]

I wonder if it could be the stock gauge because I have the same issue with my MX-7 160 with the the O-320B2D . In hot weather the oil temp runs in the high end of the green. You know, still in the green, but it makes you watch it close. I've talked to several A&P's who all say "if it's in the green don't worry about it."

I have noticed that it runs a little cooler if I fly with all 8 quarts of Aeroshell in summer instead of just 7.

[Green Hornet]

There is no doubt about the stock gauge not being accurate. In 100 degree weather ( hot & humid my oil gauge skirts the red line). After I had the EI analyzer installed no matter what the ambient temp. The oil temp reading from the EI system was lower by a at least 25 degrees F or more. A64's question that I am struggling with is at 100 degrees hot and humid day. What oil temp am I seeing in these cond.. Extrapolating I think it is 210F but I need to verify this in this condition with the EI system. My gut tells me this engine runs hotter than other engines at 100 OAT even if the stock gauge is wrong and therefore the engine is not broke.
A64 do we correlate with your stock gauge skirting red line barely in the green??

[a64pilot]

My stock gauge runs one to two needle widths from the red line. I have an engine analyzer with digital oil temp and it's from this analyzer that I'm getting the exact temp's from. The stock engine instrumentation is only good to determine trends in my opinion, it's not good enough to get any real numbers from. It's not just a Maule thing either, it's other aircraft as well.
These aircraft were designed way back in the day, now we live in a digital world. Sometimes too much information is a bad thing. Sometimes we expect precision from things that aren't precise merely because we can measure with precision now.

[Skystrider]

Just as another data point, my O-360 does the same thing, always runs in the high part of the green area. Doesn't seem to matter if it is cold out or hot. Always about the same reading.

[Green Hornet]

Well it sounds as if we have correlation even if the stock gauge is only an indication. I would bet that since we both have EI systems we could agree with plus or minus a few degrees. IMHO the Lycoming 540-IO runs hot in hot humid climate. I will give you feedback ASAP.

[a64pilot]

Well,
I guess I'm tipping at windmills. I E-mailed Exxon about how hot could I run their oil continously before it became a problem and this is their answer.

Jody,

Exxon Elite is good to red line. I don't know what red line is for this engine off the top of my head but it is usually in the 240-245 F range.
Exxon Elite is highly oxidatively and thermally stable and will withstand temperature better than other oils. At the temps you mention, I have no concerns that you are getting adequate protection from Elite. In fact, at those temps you are very effectively removing any moisture that might be condensing in the oil.

But you are generally right regarding shortening your drain intervals. If temperature were a concern (and it is NOT), shortening the drain interval is an appropriate corrective action. You must be doing your research!

Please let me know if I can answer further questions.

Blue skies.

Stephen M. Sunseri
Area Manager - Eastern U.S.
ExxonMobil Aviation Lubricants
Tel: 804-378-0002
Fax: 804-378-1493
Email: stephen.m.sunseri@exxonmobil.com

[N6EA]

Jeremy had a set of jumpers that were made up with the correct resistors to check the function of the stock Maule gauges. He demonstrated their use at Johnson Creek a couple of years ago. They were also available from the manufacturer but I don't recall the name.

You might drop Jeremy an email and see about buying the oil temp jumper to verify your gauge...