I have a 1990 f250 with a 4 speed auto trans. Transmission normally runs 150 Degree to 175 range. I have a small uxillary cooler. Ocassionally, I haul 4k lbs of dead weight( 2yd of gravel) in the bed and the transmission will climb to 200 to 225 range. Does this drastically affect fluid life or is this ok. Transmissions been power flushed twice with reg ATF and has only 80k Miles on it.