wow 20k on my tranny and now i changed to redline mt90 and now 4th and 5th grind pass 7k rpm

 

that's because your using mt-90 you goof. It's too light and doesn't allow the syncros to align fast enough cause it's too thin. You need redline 75w90 NS for the tranny and the mt90 is for the diff. Now you can add a bit of MT90 to your tranny oil(75w90) if you so choose but 90 all by itself is too damn light.

 

lmao^^^ GOOF lol

 

MT90 IS 75W90

http://www.redlineoil.com/product.aspx?pid=46&pcid=7

 

^ummm no it's not but good try. they are both 75w90 but not the same.

http://www.redlineoil.com/product.aspx?pid=47&pcid=7

 

ummm i thought it was MT-90 for your tranny and 75W90 for your rear differential

 

^your prob right. what do I know we'll let the experts sort it out. Lets go back a few post and try to correct my self. MTL not 75W90 NS

let me put the goof cap on.

 

I'll stick with my tried and true: Redline 75w90 in the diff and MTL and MT-90 mix in the trans. Or even better for those that like to play with the trans a little harder than most, 3/4 Redline 75w90 and 1/4 of Redline ATF...works like a charm!

 

well that is just what i've got after navigating the oil threads don't trust us the goofs

 

What wrong with factory diff and tranny oil? Has worked great for me for 100,000 miles (obviously not on the original fill).

 

mmmm from what i've been said mt-90 is one of the best oil to put in our tranny! let the experts explain please.....

 

All I can say that MT-90 meets Mazda specs and about 90,000 of the 138,000 miles on my trans have been on MT-90

 

MT-90 is too slick for the synchros to line up when shifting fast at high rpm's. MT-90 is good and great stuff just not for a rx-8 with it's high rev. You need something with a bit more friction. We also have brss syncros so that pretty much throws out the GL-5's. There are a few GL-5's that do not contain sulfer but they are hard to come by so ither stick with oem or redline MTL, MTL with a bit of MT-90, or as stated by I8U 75w90 with ATF. If you fill like trying something new contact Charles R Hill of BHR and he may hook you up with ENEOS from Nippon. Worked well for me but I decied to change for no reason other than the tried and true MTL / MT-90 mix.

 

Doesn't RP also meets mazda specs?

 

I thought this thread was about Red Line?

As for Royal Purple I use their motor oil , but their gear oil products as well as Amsoil receive positives reviews too. I do not have anything negative to say about any gear oils.

 

mobil 1 lol

 

You should stop with this nonsense, mt-90 is a good oil for our transmission. Things like "too slick for the synchros" etc are out of this world and any good search on this board will return the exact opposite of what you just wrote.

 

I had my concerns and I contacted Redline Tech support before I purchased Redline gear oil. The Tech stated "use MT 90 in RX8 manual transmissions as it does not have a Zinc Modifier.” He went on to say “the Zinc Modifier causes the gear oil to be to slick and not stick to the synchronizers.” I put MT 90 in and I am having good success. The tech said that MTL has the Zinc Modifier in it and it is good for the Differential. I had Zinc Modified gear oil in my Transmission for about a week and drained it due to grinding issues. I replaced it with MT 90 and all is good. If anyone has any questions about Redline products, call the Tech line and they will call you back if they are not able to talk when you call.

 

I used about 3 quarts of MT90 in my tranny and all is well. Is 3 quarts too much?

 

Mine is usually full after just short of two. I doubt you could really overfill it though, it would just pour out the plug you fill it from.

 

^I'm pretty sure AJ's Shinka was joking there
And you can overfill it if you pour the oil through the shifter and don't remove the fill plug.

 

I used MT90 with a bit of MTL or just straight for a long time and was pretty happy with it.
Until I tried the Eneos stuff which blew my mind.
I'm never going back to the Redline stuff in the tranny.

 

wtf

dude ... you have no idea what you're talking about ... please keep those bs to yourself .... seriously ... please ...

 

Well it appears as if I have been missinformed by this forum once again. If I gave a damn I'd go back and find the thread discussing MT90 not allowing the syncros to align fast enough. To bad because I couldn't care less.

 

I haven't had any trouble shifting quickly, but haven't really done much speed-shifting since my swap to MT90. I have noticed it is very difficult to get the car into 1st now with MT90. I didn't notice it at all before with what I assume was OEM oil (48k miles), but the weather also wasn't as cold before I swapped. Once the car warms up, it is fine, but in cold weather, going into 1st at anything over 10mph is pretty damn hard.