Second Oil cooler

The Return Oil line contains more air than oil, so a cooler there would be very inefficient.
Most people have problems with LOW Oil temps so your airflow may be the real problem.
My cooler is 4.5" x 9" (40in^2) and it is more than adequate.
It tends to Over-Cool during the winter.

It would help if we knew what plane you have and how it is plumbed.

Not sure what your yellow range is but, anything under 250f in climb and 225f in cruise of ok. If you use Mobil 1 4T you’re safe to over 300f.

High oil temp will bring the coolant temp up also so that’s something to think about.

Ed

Bill,  Thank you.   My plane is a Rans S-20 with a Rotax 912is.  The oil cooler 6" X 4.5 and  is mounted in the very front of the cowl but because of space restriction it is not fully exposed. ( Picture attached) I have just fabricated an extension to the rear bottom cowl to try to increase airflow by creating more negative pressure at the rear. Weather has kept me form testing yet.

My coolant radiator is located at the rear bottom of the engine compartment so that is not an option for the oil cooler.

Hi Ed,

My yellow range is 230-248deg F Max is 266 per OM.  I will look Mobil 1 4T i am currently using AeroShell Sport plus 4.

Scott

Re-Reading this;  I am not sure you have a problem.
If you are seeing the mid 230's during a hard climb; that is normal.
Does it drop back to <210 after leveling out and <200 in a descent?

Mobile 1 Synthetic Oil and Lead(100LL) do not play well.  Mogas only!