Oil cooler study , with or without thermostat?

[Bazda]

If your running at the limits of oil temps, a thermostat only passes say 70% of the oil into the cooler. It usually does not pass 100% of the oil to the coolers.

For road cars, def a thermostat is the way to go.

[B24 SW20]

I cant see the point in having a oil thermostat unless you live in a climate where its cold enough to snow for months which really cuts out 99% of places in Australia.
I run a 18 row cooler fitted where the IC was on my sw20. After 8 laps on a 30 degree day it did not get over 90 degrees. After removing the engine last week, I could not believe all the cooling pipes and oil thermostat directly below the exhaust manifold. It OK for the first 5 minutes but after that it would be a constant issue of trying to keep it cool not warm it up.
If I wasnt running a oil cooler the first thing I would do is remove all the external water and oil piping which runs under the exhaust manifold and to the throttle body as they are not needed here in Australia, then test it to see if there is a difference. Chances are thats all you would need for day to day driving and a few country runs. Add a cooler if you are doing more than that but have the cooler fitted in front of the engine not behind it in the hot air from the engine and exhaust.