I just bought a 90' Mustang GT, obviously with the 5.0. It's in beautiful condition with only 70 K on it. It has an oil leak, and im told it just needs rear main seal and valve covers. I was told by a mechanic thatit would be about $500 of work, and that it needed to be done immediately or I would blow the engine. Sounds fishy to me, as the car has been fine. Im used to my Jeep, which I still have for the winter. Does anyone know if this work should be cheaper, and whether or not it is so important to be done right now? Also, I don'thave a lot of cash to throw around, but is there any inexpensive mods such as shift kits/etc. that I can do for more HP and better performance? Any suggestions would be appreciated. Thank you.