I just got a 1982 280zx turbo. Just yesterday the turbo started making a slow squeaking niose at idle. It has ~15 oil psi at idle. The guy before me used pennziol 10w50 non synthetic oil. Am i going to have to replace/rebuild the turbo, or can i fix the problem by changing the oil, and adding some sort of oil additive like pro-long? I have no previous experience with turbos so any advice is welcome.
-Justin