Originally Posted by Tavel

im gonna have to disagree with kinfiend here. some oil additives are effective at repairing minor leaks. one that comes to mind is auto-rx, but any similar agent will do the same thing.

seals are "inflated" by oil, thus sealing the gaps. (if it doesnt make sense, think of a wooden boat. wood expands when wet, so the gaps between boards are sealed by wetting the wood...simple). sometimes the seals get gunked up and oil can't reach them, at which time they dry out. dry seals dont work. proper oil additives will clean the gunk away, freeing oil to reinflate the seals.

but again, this only works on MINOR leaks. if the seal is physically damaged/cracked it will not work.

the belt squeaking could be caused by oil, it could also just be age. you may want to replace them if they're still original.