Im goin with this

 

They're selling Mobil1 gear oil @ like 18 bux per quart around here. complete rip off.

I use RedLine for almost 10K miles already. Seriously speaking it never grind when cold. Even @ 20f outside. So I dont know why some ppl said their tranny grind with Redline when cold.

Oh, Its MT-90 btw. I changed it twice already so not much old RP Maxgear stuff in there I guess.

 

I'd just go with the Redline.

 

I'll vouch for Mobile One.
Benn using it on the street and track for over three years in the 8

 

All better quality gear lubes need a break in period (usually 50 to 150 miles-depending on driving conditions). It take a bit to squeeze the old oil surfaces out and to impregnate the new oil surface in.

It is not like engine oil that is constantly being forced to circulate, gear lube must be lifted into the gears by other gears that are typically submerged.

That is why I am always skeptical about people that claim Brand X oil solved all their shifting issues or rear end noise issues as soon as the changed it and just drove around the block.

 

I wanna try Mobil1 too but not for 18 bux a quart (locally)

Will try it next time ... order it online

 

Barrel of Oil was down to 48 bucks. Lets hope oil prices on the retail shelf go down soon.

 

It's only three, you shouldn't be drinking yet!

 

But its so fun! ask Swoope! beer05: ah...

 

I don't know does it tell us something about the GL-5's effects on the tranny, but the 02-08 manual says GL-4 or GL-5 for the 6MT tranny, and the 09-manual only prefers GL-4.

Was there any changes in the 6MT tranny for the 09 model?

 

Didn't they switch to the Miata tranny? Both are Aisin trannys. S2000 is also Aisin. What does the S2000 tranny use?

 

About 500 miles on the Motorcraft oil now and it's still getting better. The cold shifting has improved and the warm shifting is to the point where I just have to nudge the shifter in the direction of the gear I want it to go and it just sucks right in. Amazing...

 

if it means anything, i use redline MTL in my impreza. the subaru transmission is quirky and has it's own share of problems and it made a world of difference, especially at the track.

my rx8 grinds when cold and has issues up/downshifting into 3rd or 4th gear at the track on stock gear oil. i plan to switch to MTL again..

 

To the poster who is running and racing using MTF only for tranny, isn't that the wrong viscosity? I want to use maybe 75% Amsoil GL4 syn, and then maybe 25% MTF just to help protect the synchros.

 

Peugeots have had the exact same specification synchro's as the '8s, for the last 20 years, they exhibit the exact same problem with GL5, or even incorrectly specced GL4 oils - poor shifting, synchro wear, etc.

Between the enthusiasts we must have tried hundreds of oils between us, and everybody has come back to the one specified and developed for the synchro's by Peugeot and Esso/Total - now sold commercially as Total BV 75w80 ( GL4+ ) - it's gives the best shift quality out of anything - including Redline/RP/Amsoil/Millers/Silkolene/Torco, etc.
Might be worth trying.

 

I believe a previous poster using AMSOIL incorrectly recommended the wrong AMSOIL transmission fluid.

RX-8 6MT owners selecting AMSOIL should choose:

AMSOIL Synthetic Manual Transmission and Transaxle
Gear Lube 75W-90 API GL-4 (MTG)

We should not be using the SynchroMesh 5W-30 transmission fluid AMSOIL sells.

The recommendation for the differential fluid (AMSOIL Severe Gear 75W-90) was correct though.

I use both and found improved smoothness and noise in the transmission and differential, but I'm sure it would be better with any good synthetic.

Just make sure NO GL-5 in the transmission....

 

There is nothing wrong with GL-5 fluids for our transmission. I've already taken a UOA at 7,000 miles and there was no unusual levels of dissolved yellow metals in the sample. I'm currently at 16,000 miles with this same fluid and there have been no current symptoms of syncro damage.

For reference: http://blackhaloracing.com/technical...abs-eneos-uoa/

 

So what would be your explanation for Mazda not recommending GL-5 transmission fluid on 09+ models? I believe 04-08 and 09+ have Aisin transmissions.

So if we use GL-5, are you going to be guaranteeing our transmissions? We for sure know that GL-4 is fine for all RX-8s.

 

Nothing can be guarenteed. That's why companies have warranties.

I have no idea why Mazda doesn't recommend GL-5 fluids so I couldn't speculate.

In all, I have had GL-5 transmission fluid in my own RX8 for nearly 25,000 miles. I had Mobile1's 75w-90 GL5 in for about 10,000 miles and now the Eneos GL-5 75w-90 for about 16,000 miles. I have 90,000 miles on my RX8 with the factory transmission, factory clutch and factory flywheel.

If you want to run GL-4 in your transmission that's fine. However, let's not continue the myth that GL-5 destroys transmissions unless anyone wants to offer up proof. I've already done one fluid analysis in which I specified my reason for testing as looking for dissolved yellow metals. Obviously all levels were normal with the exception of aluminum which is from my shift forks.

My intention is to set the record straight, not to tell anyone their oil choice is wrong.

 

AMSoil makes a few oils that can be used in our box. I told you what I run. Nothing more.

 

I switched to Crisco, solved every problem I ever had, my manual transmission even shifts itself now, fing amazing, most awesome mod ever

well there is one issue though, I'm really packing on the weight because the constant smell of French fries while driving keeps my appetite hyped up and I cant stop eating around the clock

 

Happy driving.

 

Hey guys !

Before reading this thread i was going to change my oil to:

- Motul Gear 300 75W-90 for the tranny
- Motul PA 90 for the rear diff


What do U guys think about those oils, and Motul in overall...?


Anyway it's kind of strange thats those problems that U described may occure since Mazda reccomends a GL-4 or GL-5 oils for their trannys and diffs.
Don't U think that they would be aware of the yellow metals issue ?

 

There isn't a yellow metal issue. I'll have my 18,000 mile Eneos GL5 testing results by the end of the week or early next week.

 

I haven't done any UOA so I can't say if the issue was yellow metal. And my issue occurred only at redline going 3 to 4. This is a ~90-95MPH shift. I would have expected if there were enough track to redline 4th and 5th, say a track like road america, the same issue would have occurred there but I have no proof of this.

I suspect under normal street driving conditions there may never been a noticeable issue. Or it may have taken many many more miles to expose. I was still driving the car on the street and wasn't having shifting problems. But it was enough of an issue at the track that I needed to switch it out.

I went to GL4 spec and the issue immediately went away. I ran the same track in the same manner after the switch and the trans performed flawlessly. I'm no Michael Schumacher but I'm not sure what else I could blame for the issue than the fluid?