3 Answers

You can lose your transmission. Get the seals replaced.

if you have a manual you will sieze the gear box,,,if you have a automatic, CAR  WONT GO,,,,,,,,,, have a good day

Describe leak? I have an F350 Ford that had a leak for a year before I could get it in the shop. If its just a drip or two,  check the transmission oil level, or have someone do it if you don't know how. next smell the dip stick....Even if you have never smelled burnt transmission fluid before you will know!! If its smells burnt get it into a shop, Chances are its gonna need some work if not a complete overhaul. And like terry says  this is concerning an automatic. Ya A manual is gonna tie up bearings and destroy it really quick...