There's grimy, oily mess all over the tailgate after a twenty-minute highway ride. I noticed the glass seeming to get wet even though it wasn't raining. When I stopped and checked, there was a mess. I cannot tell whether it's from the exhaust pipe or somehwere else. I've been told I have a rear seal leak--could this just mean the leak has gotten worse?

Also, I have notice auto tranny fluid pooling under the parked car; where do trannies "tend" to leak?