In my car (not an EK9, but turbocharged motor) my temperatures on the road are usually about 85-90c. I use a good fully synthetic oil, which has shear stabability up to around 130c.
Not been on a trackday for a while, so don't know what my temperatures would reach, but would likely get to 130c.
I have an oil cooler but never fitted it, because in the winter or on cold days, the car struggles to get to 80c oil temperature unless on a wide open road (motorway), takes longer to get to temperature on short journeys and stop start traiffc.
Reason I never fitted the oil cooler, even thou it has a 80c thermostat is because the extra oil capacity and oil filter relocation helps cooling in itself and could delay the oil warm up process even longer..may be just margingly?
I was thinking of fitting it and and placing some sort of steel removal sheet in front of it to block of flow which could be removed for track.
I'm selling the car now thou and probabaly buying an EK9