Can I switch back to synthetic oil?
I have been using synthetic oil. I recently had the head gasket replaced and
the auto shop used regular oil on the repair. Is it safe to go back to synthetic
oil or should I stay with regular? Getting ready to go to Oil Stop for a change
before a long trip. The car has been running just fine. I have a 1992 Corolla
wagon, 250,000 miles on it. Thank you.