Hi Guys. I’ve used the search function, but I’m after the final decision. What transmission and differential oils do you recommend for my 1993 RX7? I’m after smooth shifting and long trans/diff life. I just took my RX7 to the dealer for all the recalls and I asked to have the trans and diff oils changed. For the diff they used a 80W-90 gear oil (GL-8945) and a limited slip additive (992694). For the trans they used automatic transmission fluid (DEX1139 ATF-DII). Will this ATF harm my transmission? My owner’s manual recommends “API Service GL-4 or GL-5 (SAE 75W-90)” for the transmission and “API Service GL-4 or GL-5 (SAE 90W)” for the differential. Should I use a mineral oil, like Castrol, or a synthetic oil like Red Line or Royal Purple? Thanks.

 

Couple of questions:

1. Do you have a manual or auto FD? If it's a manual and they put ATF in, find another shop. The manual is right.
2. You searched? I can't believe you couldn't find any threads dealing with the exact questions your asking.


fwiw, On manual FDs, I think most here use synthetics... NEO, Royal Purple and Redline are common. Personally I'm using Redline MT90 for the transmission, 75W90 in the diff.

 

I was a little surprised that they put ATF fluid in my manual transmission. What are your opinions on Amsoil gear oil? I’ll try the search function again.

 

neo synthetic..

 

https://www.rx7club.com/showthread.p...smission+fluid

https://www.rx7club.com/showthread.p...smission+fluid

https://www.rx7club.com/showthread.p...smission+fluid

https://www.rx7club.com/showthread.p...smission+fluid

https://www.rx7club.com/showthread.p...smission+fluid

Amoil is probably just fine as long as it's the right viscosity/weight. ^These are just a few of the latest threads I found using "transmission fluid" under a 3rd gen. section search.
I wouldn't drive my car very much until the ATF is drained and proper fluid is put in. If that's a MAZDA shop, you should call the district office and report them.

 

I'm really a big fan of Redline. MT90 for the trans and the 75/90 gear oil for the rear.

For what its worth, people recommend using Redline ATF in manual trans of BMWs e36 model. The ATF did feel better than the MTL in my 325s trans. Don't know why you would do that in the 7 though.

 

Probably because they're used to working on American cars. My manual T-5 Mustang GT uses ATF for trans fluid.

I think that almost any 79/90 trans oil in the trans and 75/90 gear oil in the diff should work, since you should be changing it every 30k miles.

I do run Redline, but it degrades like any other oil and needs to be changed at regular intervals.

 

Just use Redline.

 

I could understand that if it were a local shop not experienced with our cars. But a dealership? They should still have the manuals.
Do the 8s or any of the other late model Mazdas use ATF in their manual transmissions?

 

I'm using Redline MT90 for my tranny and 75W90 gear oil for my diff. I have noticed a huge difference moving the the redline products although my 5 speed can be a bit notchy at times. I've heard Neo might be alittle better, less notchy from owner's I have talked to that have used it.

 

Batman, is that Zaino Bros. on your car?...that paint is purty!

 

yeah, how's u know that i use Zaino on my car?

u stalking me?

 

No...your car looks like all those black ones on their testimonial page...been thinking about picking up that starter pack, but don't know how much difference it'll make on a white car...I do know it makes black cars DAMN SEXY!!

 

the next best thing (which I am trying right now) is the Meguiars NXT wax.

It's really good.

The shine and is right up there with Zaino, but without all the work and layers.

If i had a light color car I'd do the Mequiars.

I've tried just about everything.

 

I might just have to try the Mequiars NXT...it's like $13/bottle, alot better than almost $100 and like you said without all those layers. I've tried Mequiars 3 step system with the cleaner, polish and wax...it wasn't too bad, but damn it took all day! Either way man whatever is on the car in the pics, very beautiful car.

 

This Mazda shop has been in business for about 25 years. I used to think they were the best in the city. Now I’m not so sure. After I looked at the invoice, I just drove home. I won’t drive the car again until I have the transmission oil replaced. I talked to the technician who worked on my car and the service manager. They said that all the dealers were using ATF in the manual transmissions of second and third generation RX7’s. I will discuss the problem with Mazda Canada on Monday. Right now I’m trying to decide what oils I want to use in the transmission and differential. Thanks for the advice and the links.

 

Of course they'll use ATF in the FD manual trannies (this is complete BS since I have drained plenty of original tranny fluid from the 5-speeds) so that u can get on the "frequent-fler" mileage program at their shop.

 

Is that the same recommended diff oil to use even if i have 2 way carbonetic lsd (metal)

 

8 year old thread necro...

-Geoff

 

Motul!!!

 

So what?

If it is on-topic, who cares?

It just occurred to me how much time I wasted replying to this - 22 seconds I can't get back.

 

Because he's asking questions of the people who are posting in this thread. Of the 3 main contributors to the thread, 1 is banned and the other 2 haven't logged on in 5 years.

-Geoff

 

^Well...I'm still here.
A short google got me to Carbonetic's website. In the FAQ section I found this.....

What oil do I have to use, can I use normal LSD oil?
No we do not recommend standard gear oil with the Carbon LSD, we suggestion using the Carbonetic Oil available from your local dealer. But if you cannot get hold of the Carbonetic oil, we have tested other brands that work with the Carbon LSD:
For FF/AWD application
MOTUL Gear Competition SAE75-140
NEO Synthetic oil 75W90RHD

For FR application
MOTUL Gear Competition SAE75-140
MOTUL 90PA
NEO Synthetic oil 75W90RHD

 

is the trans and diff oil the same?

 

Use a GL-4 for the transmission and a GL-5 for the diff.

My suggestion? Amsoil all the way.

GL-4(2.8 quarts):
AMSOIL - Synthetic Manual Transmission and Transaxle Gear Lube 75W-90 (MTG)

GL-5(1.2 quarts):
AMSOIL - Severe Gear® Synthetic Extreme Pressure (EP) Gear Lube 75W-90 (SVG)