what's are good fluids to use for tranny and rear diff for a track car? I like redline products for my previous cars.

Redline MT90 75w90 GL-4 or MT90 NS 75w90 GL-5 for the tranny?
Redline 80w140 GL-5 gear oil for the diff?

i have used Amsoil product before also but the redline stuff seems to last longer.

 

I've been using mt90 in the trans and mobil1 75w90 LS in the rear diff. Diff fluid came out yesterday looking perfect.

 

Last night I found some Red Line fluids in my closet, so this post is timely. I have 1 L of 75w-90 GL-5+ with the limited slip additive. The FSM calls for 1.2-1.4 L (1.3-1.4 US qt) of API GL-5 SAE 90, so I can use it but will need another liter.

I have 2 L of MTL, which is 75w-80 GL-4. The FSM calls for 1.75 L (1.85 US qt) of GL-4/5 SAE 75w-90, so I shouldn't use it.

I've never heard any negative feedback about Red Line gear oils when used appropriately, but I haven't been reading about RX-8s for very long so I don't know if there's a better option for the S1 transmission.

 

For manual trans, another good fluid is Ford Motorcraft XT-M5-QS. You can get them at any Ford dealer.

 

^^Have pretty much run them all and that’s my current recommendation for both the S1 and S2 manual transmission. Sooner or later the factory S1 trans will fail regardless.

Rear diff is less picky. I have the OS Giken LSD now and use their special fluid, but the usual RL GL5 products are fine for factory LSD.

 

ill try the ford tranny fluid for the next fluid change. i just put fresh Amsoil in that i had a few quarts left over.

do you use 80w140 GL-5 or 75w90 for the diff. i don't know how hot the diff will get after 30-40 minutes race.