I just had a bunch of maintenance work done on my car along with the tranny fluid. I had had Royal purple put into the tranny and now my tranny is being really fussy, so i'm looking to swap the oil again. Looking around on different fourms, ppl stray away from Royal Purple and it seems the standard is Redline MT90. However, it seem the MT90 isn't very good in the cold but is fantasic once warm. I've seen that Idemitsu 75w90 does the same great job at any temp. I've also seen pll say that the miata shares the same tranny as the series 2 and there all about the Ford Motorcraft 75w90. I've heard great things about it but there doesn't seem to be enough reviews on it for RX-8's.

So if anyone has any experience with any of these 3 oils please share your experience so i may choose a good oil.

 

None of them, just use factory factory Mazda gear oil and change it yearly.

 

To be completely honest, you are shooting yourself in the foot here

You are looking around and see that people prefer various different oils. So you ask for more people to share their preferences? As 9k's response illisustrated, you will actually just add more options and reasons for and against each, and still not be left with a consensus


In the end, I would just recommend that if you aren't sure, pick one and try it. If you like it, it's solved. If not, you are out only $40 or so and can try something else.

Like I put MTL in my NB Miata's transmission after this last engine replacement based on high recommendation, but find that I prefer MT90 over the MTL. I use MT90 in my 8's transmission, and have been happy with it for 80k or so since I first made my own choice about the transmission oil. Might something technically work a bit better? Maybe. But I'm happy with it and that's all that really matters to me.

And even through daily driving in the winter, it was a bit thick in sub zero temps, but it was never an actual problem. Warms up fast enough that even this little bit of change disappears quickly.


And Royal Purple isn't the best idea, as it seems you are discovering. Too many people with syncro failure relatively soon after switching to it for me to be comfortable with using it. May not be conclusive, but the suggestion is enough when there are plenty of other oils that work just fine.

 

^+1

same goes damn near everything else.

 

All I can say is, since I swapped the royal purple for the MT90 the trans has been perfect.

 

^yeah I had issues with Royal Purple, lots of hard shift problems. I switched over to Eneos from BHR about a year and a half ago. Eneos is great stuff, fixed all my shifting problems caused by the RP gear oil. Just bought another case from BHR this week.

I can't find it now but I remember another company (I think amsoil) did several oil analysis on other gears oil and found issues with RP as well. I really wish I could find the report, after reading it I drained the RP out of my tranny as fast as I could get Eneos to my house. I do remember that Redline performed really well in their analysis.

 

I have used MT-90, MTL ,Motul 75-90, Motul 300 syn, Eneos, Amsoil 75-90...and they all work about the same Differences in price and availability tend to make up my mind at the time

I have Motul 300 in it right now...and It seems to work well...

Diff has been a PIA though. The Kaaz LSD doesn't like very many oils...their oil works well..and the Motul non-syn with additive works well...but I tried about 4 others that didn't

 

This is what I used when I did mine. Works perfectly. No complaints. Direct from Mazda parts counter.

 

And 80W-90 for the diff right godess?

 

Anyone have any experience with idemitsu? Looks like they specialize in rotaries. I can make a trip to grab me some, but wondering what ppls experience with it is.

 

Idemitsu sells good oil, but depends on the price it might/might not be worth the extra hassle.

 

I put Eneos in, and it's very nice.

 

 

ford motorcraft worked best for me compared to whatever mazda had in there from the start, and redline.

 

i have some eneos in my garage, have another autox coming up, after that gonna drain the red line out and eneos in.

same thing for rear diff, Mobil out eneos in