I want to change my transmission an diff fluids but I don't know what kind and how much to put. Can you guys help me out?

 

Assuming manual tranny, 90wt gear oil is what to use for both. The syn work better IMHO. Any good brand
should work. If you have LSD you will probably need an additive as well.

 

Thanks. Do you know how much liters of each?

 

What year is your 7? Manual or automatic trans?

 

It's a 1985 rx7 gs coupe. Manual tranny.

 

1.3 and 1.7 liters....best to get 4 quarts. Use GL-4 for the transmission. GL-5 will etch the brass syncro rings. GL-5 is best to use on the differential because it has superior shear strength.

Since you are doing it yourself, saving big bucks, and you only do this every two years, why not splurge on AMSOIL or Royal Purple?

 

I've run 75w-90 gear lube in the transmission and rear differential with great success on many of my cars. Synthetic is recommended of course, I wouldn't use a conventional oil in my stuff anymore.