what type of oil does the 89 RX7 use?
Actually the 89 RX-7 uses good quality mineral motor oil (20W50 grade API SF) which must be changed religiously, the manual says every 7,500 miles or 12,000 km but I recommend every 5,000 miles. If you do want to use full synthetic the only way to go is a very low ash content oil like Royal Purple, as the rotary engine burns some of the oil you want to reduce the deposits in the engine caused by this. Also regularly check the oil level (at least once every two fuel stops).
Search Mazda RX-7 Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Mazda RX-7 Experts