Mine was a Roush 427IR. I was losing coolant until I added a expansion tank to the coolant system (I got one of those beautiful Kirkham billet ones). In city driving the temp was high while on the highway it wouldn't warm up. The radiator is so oversized that I went to a higher range thermostat (190 I think) and that helped a little. However, the engine
oil cooler then became a secondary radiator and prevented
oil temp from getting much over 180. Some people here discussed a thermostatic bypass for the
oil cooler but I don't know where - search might find it but there are so many topics on "oil cooler" that it didn't jump out. I do recall there is a JEGS part that is used. I sold the car before I put it on (it was going to be a winter project) but I suspect if the oil cooler were tuned to balance oil and water temp that the thermostat could have been backed off.