I did a search and didnt see anything on transmission fluid saw a lot of problems with peoples transmissions but i didnt see any one recomend a certin brand. I went to a few places and the only manual tranny fluid was the royal purple synchromax, and i was wondering does it matter what fluid you use as long as its designed for a manual transmission?

 

A lot of people are happy with Redline gear oil, MT90 in the tranny

 

Syncromax is the wrong fluid to use and I'm sure the reason for many people not being happy with RP. Personally I use RP MaxGear 75W90 in the transmission and differential. Redline and Amsoil are also good choices.

 

so i could anything that is atf 75w90? does it matter if its a synthetic oil? to me it doesnt matter the cost because whens the next time i have to change the tranny fluid 50000 miles.

 

 

why do people make such a big deal about RP?

its fluid........

 

When you have a picky transmission like the Aisin in our RX8; not just any fluid is just "fluid".

I'm using the BHR recommended Eneos 75w90. A bit loud when warmed up, but that is totally normal according to BHR. Smooth as butter.

 

Glad to hear it. I tried a lot of stuff in my tranny including the RP Maxgear and the Eneos is by far the best IMO.

 

Royal purple 75w-90 synthetic trany/diff fluid works out great. Shifting definitely alot smoother than before.

 

https://www.rx8club.com/showthread.p...ht=transmisson

People dont like Royal Purple tranny fluid because its a GL-5 fluid which has reactive sulfur which can chemically wear brass synchros... GL-4 Fluid has less a less reactive sulfur content or percentage which isnt supposed to wear the Brass synchros- From what I have read...

I do not have any personal experience with RP tranny fluids for the 6MT RX-8, I have used their fluids for when I had my auto RX-8. I used their ATF and 75W-90 for the diff...

Since I do not have any personal experience with RP tranny fluids in the MT RX-8 I cannot say the fluid will actually do this but I do not want to take a chance, which is why I chose Redline MT-90 for my Transmisson fluid and 75W-90 for the Diff. Rather safe than sorry....

 

well i can certainly see (different) gear oil makeing a difference on noise concerns.

But the people who claim their car got noticeably faster when using royal purple oil in their engine...... id say their full of it until i see some dyno charts and data logs.

it all sounds like some ricer **** to me

 

A lot of us who have used it have had problems. In my case, I got a 4th gear grind very shortly after starting to use it. I switched to a GL-4 fluid (Pennzoil platinum, IIRC), and it got better, but was still there.

And, for the record, I did use the Maxgear 75W90.

 

Use the GL4, which is designed to be gentle to gold metals like brass synchros.

Many a parts counter guy will do their best to sell you the GL5, saying things like "supercedes the GL4" and/or "replaces GL4 for all uses". Nevertheless, there is a reason Mazda specs GL4 for the tranny and GL5 for the rear diff. In my reasearch this was backed up by my Amsoil rep, who suggested the same GL4 & GL5 package as spec'd above. Wasn't even a question for him, it was as simple as "Lube for a manual tranny, you need GL4."

 

i used royal purple before and my tranny was grinding from 1st to 2nd at high rpms, i then switch to redline and problem solved. Stay away from royal purple use redline.

 

Where did you read that?

 

let me spell it out for you ...

r-e-t-@-r-d-e-d


.

 

I know many people using RP in transmissions, yes even in RX-8 transmissions, that have no issues at all. I firmly believe it's how the car is treated by owners that kill transmissions and nothing else.

 

RG, do you thing the diference between GL-4 and GL-5 is not a big deal? I think the problem that most people have with RP is that their local parts store only stock the GL-5 version which is great for the diff but not good for the trans. I deffinately do agree that our trans needs to be used properly. It does not respond well to voilence or rought shifts.

 

redline mt-90 in the tranny,
http://www.redlineoil.com/product.aspx?pid=46&pcid=7

and redline 75w90 + Limited Slip additive in the rear if you have L.S.
http://www.redlineoil.com/product.aspx?pid=133&pcid=4
http://www.redlineoil.com/product.aspx?pid=41&pcid=4

 

and it is a big deal. if you put the GL-5 in your tranny kiss it goodbye after about 10k miles

they are very different.

https://www.rx8club.com/series-i-tech-garage-22/gl5-vs-gl4-gear-oil-transmission-159398/

 

The Eneos 75W90 fluid recommended by BHR I'm using is GL5. I highly doubt I'll be kissing my transmission good bye anytime soon.

 

maybe you wont, and maybe you will...
https://www.rx8club.com/rx-8-discussion-3/possible-clutch-bearing-transmissino-issue-184930/

 

Not all GL-5 fluids have the same amount of chemically reactive sulfur, I remember reading some have more and some have less than their stated value of GL-4 or GL-5... so far Eneos 75W-90 is the only GL-5 Fluid that works in the RX-8 Transmisson and is fine...

 

did you try the ams oil

 

I'm well aware of that. Unfortunately, some aren't.