93 Volvo 240 auto. sedan. with +t 13c 10lbs boost-huge trans cooler. The trans is fine when you first start the car in the morning. After you drive it for 3 miles it starts slipping then eventually wont move. If you let it set for 15 minutes you can drive it for few miles then same thing happens. The fluid is full and it looks clean. I changed fluid when I added trans cooler (4 quarts) uiversal trans fluid. Is it worth dropping the pan and changing filter? or is trans done for?