I forgot how sweet this stuff is, at least for Rx-7 applications. I've used it on multiple Rx-7 transmissions before, turbo and non turbo. But the last time I had to fill up my recently rebuilt T2 tranny I went with Mobil 1 synthetic 75W-90 because it was easier to find.

Apparently using the Mobil 1 was a mistake. Over time it became harder and harder to shift into 3rd once the gear oil had heated up. My transmission which had less than 4000 miles on a rebuild would grind and occasionally not even go into 3rd. I found myself double clutching 3rd gear. Sometimes even with double clutching it would still grind.

So I just switched back to Redline MT-90. All the grinding is gone. My 4000 mile transmission feels like a 4000 mile transmission again.

 

That's why Mazda says "High quality synthetics".

 

Mobil 1 isn't real synthetic anymore. They will not release the formula, but it appears to be just Group III base stock, maybe with some Group IV thrown in. It's not bad, but it's not comparable to real synthetic oil like Red Line.

 

A good friend of mine has a Lotus Esprit (the one in my avatar). If you guys know anything about Lotus cars, 60% of the time, they work everytime.

Anywho, he swears on the stuff for his transmission (which aren't the best in the world). Took away all the shifting issues. If it's good enough for a Lotus, it's good enough for our cars : )

I use nothing else.

 

hmmm i havnt had good luck with redline mt-90 i bought a 88 TII and swapped to the redline fluid, first time i drove it after that 5th gear would grind everytime...so i let it stay like that for like a month then i swapped it to pennzoil syncromesh and the grinding went away...it also seems way quieter and smoother than it was with the redline...maybe my tranny just didnt like it but dunno.... .02

 

My transmission is a PITA to shift. Then again my car is very old, and very high (albeit unknown) miles. I did change oil this past december (a whopping 500 miles ago), but it's still rough. Do you think I should go with this fancy oil or just source a new trans. I am nearly 100% certain it has 200k miles on it.

 

Make sure your clutch hydraulics are in top condition (including fresh fluid) before abandoning your transmission. When I bought my current car with 28K miles on it, I put Redline MT-90 in right away and I still noticed a slight grind upshifting from first to second when it was cold outside. When I changed my clutch fluid a little while later, the grind went away. So I decided to replace the clutch master, slave and hose (because there was a fair amount of black debris in the old fluid) and now it shifts like a new car.

 

MT90 is great stuff.

 

Clutch master has maybe 1000 miles on it. Slave has maybe... 10 miles on it. I don't drive this car because it's usually broken, or when it's running I'm afraid it's going to break.

 

lol spoken like a true rotary enthusiast