Transmission Leak on 1996 GMC Jimmy

96 Jimmy with auto Transmission leaks between the pan and the case when warm out side and you travel a distance of 10 miles or more now that it is cold out it don't leak, when it is hot it just sprays it out every where, I have changed the Gasket several times, put on a high priced silacone gasket and it was worse, put on an alum. Pan nothing seems to help but the cold weather, It has a new radiator, the fluid looks and smels ok. Don't Know

Asked by for the 1996 GMC Jimmy
ck front seal are you saying 4x4 is trans pan leaking
Transmission Pan Seal leak FRONT and REAR Seal ok only leak from pan gasket but have replaced several times and I know the pan is good and the Gasket is good I am uesing a rubber Gasket I have even put sealer on the gasket and let it sit over night and it only leaks when you are trveling over 10 miles and when it is worm. Chilton book says it could be a plugged breather / vent tube I have not tried to blow air threw the tube yet, just wondering if anyone has ever ran into this before, the transmission preformes prefect just has this stupid leak.