Members,

I purchased my FD new in 1993. It has been serviced, at least twice a year, from the very beginning, by one of two Mazda dealerships, most recently a few days ago. I noticed on this ticket that Mazda bulk synthetic oil was used this time for the oil change. This is new. I am almost certain that every oil change to date has used mineral oil. (I will look through my sizable stack of service tickets to confirm, but I believe the mineral oil has always been Castrol GTX 10W30.)

Today I spoke with the tech who did the work, and asked about this. He (relatively unfamiliar with rotaries, I think) was surprised to know that rotaries might have issues with synthetic oil. He had simply used the Mazda bulk oil they currently routinely use. He left to check with the shop's certified rotary mechanic, and (evidently) was told that I should have no concerns.

What say you all? Leave as is? Or have the shop drain the synthetic oil, and replace it with Castrol (or some other mineral oil), with a new filter. More info: ~165K miles on the car; ~115K on the second engine, a warranty replacement; sequential twin turbo was replaced with a 99-Spec JDM sequential twin turbo in 2000 or so (I forget the mileage); for each of the last 20 or so years, I drive my FD less than ~500 miles/year, spirited, on curvy, two-lane blacktop.

Thanks in advance for your thoughts.

By the way, my power steering fluid return hose and flexible brake lines required replacing for my FD to pass state inspection. The shop was able to source an OEM PS fluid return hose, but wasn't able to not source OEM brake lines. I learned about SakeBomb Garage brake hoses here on RX7Club.com, so I ordered a set. The tech installed the hose/lines today (with complete fluid flushes at my request). He was very impressed with what appears to him to be very high quality brake lines. Thank you all for pointing me toward SakeBomb!

rx7diver

 

There is absolutely no issue with using a good Synthetic oil. I'm going to go as far as to say it's a mostly baseless myth that you have to use mineral oil, just don't use garbage oil. I can't remember where the source is atm, but I believe Mazda used synthetic in their competition rotary powered cars back in the 80's. I've ran Royal Purple in every rotary I've owned since 2006 and I've had zero issues (one of which was an RX-8 that had 164,000 miles on the original engine when I sold it.)

 

I can’t believe the issue of mineral vs synthetic has never been discussed before.

 

Never once.

 

This topic was beat to death when I joined the seven club almost fifteen years ago.

 

I did research RX7Club.com before I posted. I concluded that my particular situation had not been addressed, though.

At any rate, it turns out, my concern was/is unnecessary. I looked back through my stack of service tickets last night. The Mazda tech who personally serviced my FD from almost the very beginning retired a couple of years ago. Turns out that the very next time my FD was serviced, synthetic oil was used--which means synthetic oil has been used in my FD for a couple of years now.

I haven't observed any of the problems I've read could result from this (i.e., from switching a very high-mileage 13B-REW that has historically lived on mineral oil, to synthetic oil). Maybe because I drive my FD so relatively little, and/or maybe because I am very gentle with the drive train (even though I like "spirited" driving), I have been spared the problems (e.g., suddenly using excessive amounts of oil) that others have seen.

At any rate, thanks to all of you who offered opinions/insight. I've decided to leave well-enough, alone! (You know, if it ain't broke, ... !)

rx7diver