[Low n Slow]

I have a question for the engine experts out there. I just installed a butterfly valve in the 2 inch oil cooler duct today. Now that I can regulate the temp of the oil (it was generally too low), I'm wondering what's the optimum oil temperature for long term engine life?

I've heard for years that you want the temp to come up to at least 180 to remove moisture, but I just read a post recently that claimed you need 212?

On a x-country, is it better to keep the temp at approx 180 for the entire flight, or after 180 is reached and maintained for a while, is it better to lower it to 140-150 (or lower?) for most of the flight?

 

[rwhittier]

180 is the number...

You should be shooting for 180 degrees and the number your vernatherm tries to deliver. Engines produce quite a bit of water in the process of combustion, so it would not be advisable to lower the temp after an hour as the process of producing water never stops till you shut it down.

Also as you increase altitude the boiling point of water goes down (reduced pressure, water boils more easily).

I have a question for the engine experts out there. I just installed a butterfly valve in the 2 inch oil cooler duct today. Now that I can regulate the temp of the oil (it was generally too low), I'm wondering what's the optimum oil temperature for long term engine life?

I've heard for years that you want the temp to come up to at least 180 to remove moisture, but I just read a post recently that claimed you need 212?

On a x-country, is it better to keep the temp at approx 180 for the entire flight, or after 180 is reached and maintained for a while, is it better to lower it to 140-150 (or lower?) for most of the flight?

 

[David-aviator]

Out of the Lycoming operators manual - oil inlet temperature

180 is desired above 70F OAT

170 is desired from 70F down to 0F

160 is desired below 10F

140 is minimum during continuous operation

245 is max

 

[Steve Sampson]

Tom, my understanding of the confusion about 180 v 212 is that the oil temp rises as it goes through, so in at around 180 results in out at around boiling point.