For several years I have been wrestling with high oil temps in my 360, a not uncommon problem.  I have an IO360, 9.0/1 pistons, plenum, a fairly large cowl exit area, and firewall mounted oil cooler with a Positech 4215 (8 row) oil cooler fed with a 3" SCAT off the right side baffling. 

 

In search of an "elegant" solution, I experimented with  
-the shark gill louvers for exiting air (which I no longer have)

-a duct between the shark gills and oil cooler to help draw air out

-a cowl flap

-adding a 2" duct off the right side of the engine to a "Y" into the 3" duct feeding the oil cooler

-replacing the "Y" above with a separate 2" flange on the oil cooler duct

-etc

 

When adding the additional 2" hose feeding a 2nd flange on the  oil cooler duct (roughly 40% more air volume) produced little improvement, I decided that it might not be a problem with air flow.  I then decided to try the Positech 4216 (10 row) oil cooler.  I was told by an oil cooler specialist that while the old Positech coolers were noticeably inferior in cooling to the S/W models, the new models (produced for at least the last couple of years) are roughly comparable.

 

While I have not flow in hot summer weather yet, the larger cooler is a marked improvement.  I flew 4 long ILS approaches in 50F weather and the oil temp had just passed 200F.  Previously, 2 ILSs would have the oil temp approaching 240F.  The ability to tolerate longer periods of ground operations also appears much improved.  Cruise temps are fine at 170-180F at 25-50F OAT.  My CHT's are well balanced (generally less than 20F spread at cruise) and within the conservative limits recently discussed on the LML.

 

While I know others are successful with the smaller oil coolers (especially if mounted directly on the baffles or fed with a large NACA scoop), this worked for me.

 

Regards,

Clark Baker

LNC2 360 (660hrs)