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

 

Personally if it were me I would have them change it back. 115k on the motor with mineral it's whole life. I would stay mineral. Just my opinion.
There will be many opinions on this. It's been brought up so many times.

I broke my new motor in with mineral and switched to synthetic.

 

I just read a Tech Tip about this question on the Racing Beat website earlier today. Switching to synthetic on a high mileage engine may cause problems: https://www.racingbeat.com/mazda/per...etic-oils.html

 

That's why I would stick with dino oil after that many miles. Just change it more often with the 10w30.

 

Will it cause any harm? I don't think so. Would I have the shop drain and refill with the right oil? Yes. They should have put the right stuff in, it's no big deal for them to drain and refill.

Neat to hear from an original owner!

Dale

 

Somehow I inadvertently created duplicate threads! Apologies.

I just responded on that other thread.


@DaleClark, my FD was my only car (essentially), my daily driver, from 1993 to 2001, at which I time I began my family and began driving a Honda minivan. The first few years, from 1993 to 1997, I was driving my FD from southeast Michigan to central Missouri, round trip, every three weeks or so, and this is when most of the mileage occurred. My FD looks a bit tired and neglected now, but it is still a lot of fun! Thanks.

rx7diver