I run mine on a manual switch to full on. The fans don’t really do much once the car is up to cruising speeds on the road or above. I just run them on pit out or if the car is idling when at temp.

I have my preliminary results of the 82C thermostat I had recently fitted. I had the coolant swapped from a 60/40 to a 70/30 water to coolant ratio as well in the process. To give an idea - freeze temperatures now have changed from -35C to -15C.

With ambient temperatures at 36C and cruising at 100kmh in 6th, coolant was at 86-88C (previously 89-90C) and oil temperatures at 91C (previously 93C). On idle, coolant stays at 88C though I should be able to run it slightly cooler by changing the fan trigger points.

Will run another test at night, where ambient typically falls to 26C.

I have the Full blown and Full blown radiator and Spal fans. I only got it for extra security with opening up sooner.

Another update - did another test on a long highway uphill recently.

Ambient temperatures were at 36C, with gears intentionally held lower to get more heat into the coolant, and the temps stayed lowest at 86C throughout the entire run. Oil temps were averaging 109C, with a Forester water to oil exchanger.

With the new thermostat opening at 82C I could manage only 86C - this indicates that the stock radiator does have additional cooling capacity, but not much left given in a tropical setting.

Regarding oil temperatures I am seeing a slightly more substantial drop, about 5C peak to peak. As the coolant further cools, more heat from the engine oil gets transferred to the coolant due to the larger temperature difference which then brings back up the coolant temps.

With owners in Japan reportedly are running at around 84-85C with the same setup - this is as far I can probably get with the stock radiator.