View Full Version : Oil Cooler Target Temps

09-12-2017, 11:39 AM
Replaced the CSF Racing rad with a CSF oil cooler combo rad in my '11 STi sedan and although this will work brilliantly at the track I am concerned that the oil temps are too cold for street use. Car is stock with oil/boost monitoring, AOS and this super-duper cooling. Objective is reliability at the track.

Measured at the sandwich plate with an Auto Meter electric gauge, oil temps were 225F max with the CSF Racing rad at the track. This is good.

The CSF oil cooler combo rad has a thermostat sandwich plate set at 75 - 82C +/- 2C. Converted to imperial this is 167 - 180F, which is basically coolant temps.

Now highway temps are 167F in (13C ambient) and 180c in city driving, and I'm concerned that this is too cold for winter driving.

It looks like the industry standard thermostat setting for external oil coolers is 185F but I'm learning that the target temp for oil in a street driven car should be between 215 and 240F.

If you are monitoring oil temp, what are your target oil temperatures and how do you achieve them?

09-12-2017, 03:36 PM
Those are the same temps you'd get with an STi that was never driven hard in regular driving; same as coolant. Theoretically you occasionally want to see "boiling water" temps because that's when you vaporize the water out of the oil. However, sustained 180 deg F can still separate water from the oil, but not as quickly.

Put 5000km on your oil and send it for analysis. Mention in the comments that you are concerned about water content of the oil, though it will probably show up as oxidation or viscosity loss if it is significant enough to worry about.

09-12-2017, 03:47 PM
Good idea slowpoke, and I'll use this procedure from Blackstone labs to get a mid-stream oil sample after 5000 km.



09-12-2017, 09:48 PM
on my 5.7l Camaro, i ran a 195F coolant stat, the coolant temp never went over 200F, the oil temp was 220-225F during competition. i put a 180 stat in, the engine temp stays rock solid at 180F and oil temp was 215. Ambient temp was 32C. Again, this is during track driving only as i don't street drive the car. Oil is off the shelf Mobil1 5w30. i have a remote oil cooler up front taking in air from the bottom, at the front and an elec fan on that cooler, but i have never used the fan.