oil leak

hello, new here...recently bought a 85.5 when i got up the next morning i noticed a small patch of oil on the ground...so i went to have an oil change..they said it was a leak on the rear seal..and got high mileage oil..then the next day there is another patch..so now i have two..why? and how hard/expensive is it to fix? thanks

Expense depends, how handy are you with a wrench?
Why? Old seals go bad, was the car sitting for a while before you bought it?

Which rear seal, crank, or balance shafts?

i believe crank...i put some racing oil 30w50..and it seemed to stop the leak..but i don't know if that hurts it or not?

no, doesn't hurt. Unless it's very cold where you live.

great...just curious...where can i find how the belts are supposed to go..i came today and the AC/alt belt snapped...i bought a new one..but not sure how it goes on..

Loosen PS pump adjuster to remove it's belt.
Loosen adjuster on A/C compressor for tensioning.
Install new belt around crank, alternator, and A/C
Reinstall PS belt
Tension both belts using the applicable adjusters (center turnbuckle adjusts length).

If the belts are too tight, you wont be able to wiggle them. If too loose, they'll squeak/wont turn

Good luck.