I use Amsoil and it works great.

 

MT 90, have not tried the others, has been better than every fluid I replaced so far if that helps.

 

Changed to BG Synchroshift and it's awesome!

 

So what's wrong with a synthetic 70W110 GL4 gear oil ?

 

Wrong weight

 

So it is wrong to have better cold and better hot temperature performance?

 

"Better" is subjective. As long as it provides appropriate protection without causing syncro problems, then it all works approximately as well as anything else.

Generally, a 70w110 is going to be too thick at operating temperature for street driven cars. The shifts will be a little 'thicker' feeling, and you will be sapping a fraction more power having to move a thicker oil through the gears. It's good if you run hotter transmission temperatures, like if you race the car, but over-doing it for the street.

 

If SAE 70w110 gear oil is too thick why do SAE 75w90 GL-5 gear lubes contain extreme pressure additives?

 

^ I'm pretty sure you didn't read my post entirely.

 

So use GL4 ?? im getting mine done soon and dont want any **** going wrong

 

Yes, GL4.

 

So with AMSOIL being a GL-4 I am going to be putting in my tranny, What about the Diff? Trying to find info on the product and all I find is a GL-4. What should I put in the diff?

 

You need to use a GL-5 gear oil for the transmission. You can use a 75w90 or a 75w110 GL-5 gear oil. In 2006 the obsolete SAE 90 grade was replaced with 2 different viscosity grades and were renamed SAE 90 and SAE 110.

 

my car is throwing oil up threw the overflow and into my intake hellp!!!!!!!!!!

Posted From RX8Club.com Android App

 

Search "catch can"

 

Wont find the answers in a tranny fluid thread, refine your search ability


NA 8 should not need a catch can, unless something is wrong oil should not enter the TB, yes it happens from time to time. But is usually from overfilling your oil or some other underlying condition.

A catch can is good peace of mind, but OP has a problem causing this. Catch can is a band aid, better to fix the problem all together.

 

FWIW Kings Mazda (Cincinnati) said that they have been using Ford Motorcraft GL-4 non-synthetic in bulk for MT transmission work in the RX-8 and Miata MX-5 and other Mazda's that specify 75W90. (They do not sell in quarts or case of quarts).

 

Doing a bit of thread archaeology, wannawankel?

 

These two are amazing if you can get them also neo synthetic its what a lot of the guys in Australia are using!

 

Put in the motorcraft stuff and noticed the transmission does not want to shift smoothly until it warms up. Does anyone have experience with something that shifts smoothly at lower temps but also holds up for a year with more than a few track days on an s2?

 

Just the opposite and never heard this reported before. Are you sure the right fluid was used? There is more than one type.

 

I've noticed my S2 gearbox getting a little... recalcitrant since the weather has turned cold.

I've had Motorcraft XT-M5-QS in this gearbox since I installed it and have about 12 months and 10k miles on it.

 

XT-M5-QS. I originally was going to try mt85 since mt90 has a reputation for poor cold shifting but a local race mechanic told me it breaks down quickly. Loved the mt85 in my miata though. I guess the rx8 trans gets much hotter.

 

I can only speak from my experience with it, but I just bought the ford motorcraft that the miata guys and some members here have been talking about. My S1 trans, which are kind of known for being made of glass, had issues with going into reverse from a dead stop without putting it into first gear before hand hasn't had that issue since.

I would also have an occasional grind going into second at high RPM's, as well as having to encourage it to go into gear downshifting into 2nd.

None of those problems are present now. My transmission has 135k on it, and in my case I've been really happy with the fluid. Its only been about a month or so maximum of being in there, daily driving with some spirited driving mixed in. But I'm happy with it.