Boiled clutch fluid at the track!

atropine

At least that's what I think happened. Doing long (30-40) minute track sessions at Miller Motorsports Park last Fri. Toward the end of session 3 I pushed the clutch pedal in and it stayed on the floor. I was able to lift it back up but it did it again so I came in to the pits. Within 30 seconds pedal was back to feeling normal. Inspected everywhere, no evidence of clutch leak. Car was getting very hot and I actually spewed just a bit of coolant out the expansion tank. Oil temp maxed out around 240, but I think maybe the extra heat dissipated by my huge AE oil cooler in front of the radiator led to increased coolant temps. Miller is a very fast track and with the way my car is geared, it is best suited to just leaving it in 3rd for most of the track with some occ. shifts into 4th. I wasn't shifting much, but I was running extended periods of high rpms (6000-7500). Can I flush my clutch with some higher-temp fluid to prevent this in the future? BTW, ambient temp was mid-80s. I drove the car to work this morning and it feels totally normal.