Johnboy

iTrader: (2)

I am about to change my differential and tranny fluids to MOBIL 1 75W90 synthetic gear lubricant. I have read the tech bulletins and the owners manual but for my own peace of mind, can you verify that this GL5 quality gear lube is used in BOTH the MANUAL transmission and the differential. Again,,,,the same fluid in both the tranny and the differential.

Thanks

swoope

iTrader: (5)

tran gl 4 or 5
diff gl 5.

i am running gl 5 royal purple in both.... the tranny loves it..

beers

Johnboy

iTrader: (2)

Thanks....I haven't noticed GL4 in stores before anyway. So MOBIL 1 GL5 75W90 synthetic it is! My friend swears by MOBIL 1.

yiksing

I use the Mobil 1 GL5 above as well, the tranny certainly loves it but now I can no longer shift into 1st gear until the car fully stops but I think this is entirely normal since my friend with a lower mileage properly cared for 8 still on the factory fluid is not able to do so too.

ndtechie09

i've been told to get the redline mt-90 for gear oil. can anyone comment on this over royal purple? dont know about the difff fluid

swoope

iTrader: (5)

the stuff i posted was straight from the owners manual..... i am running rp 75-90 in both... amazing stuff....

i am sure the diff between rp redline and mobile 1 are not enought to talk about.

beers

TeamRX8

iTrader: (25)

after two broken transmissions I'm switching to Redline 75/140NS

swoope

iTrader: (5)

what were you using before?

beers

HCTR154

I went to the Royal Purple in my tranny about two weeks ago. Initially, I didn't notice any difference. But after about a week, I can say that shifts are noticeably smoother, with little effort. Even 5th to 6th !

Royal Purple lubricants are top notch and highly recommended.

StixandStones

I changed my tranny and diff oil to Royal Purple 75/90 a couple of weeks ago.
The smell of gear oil is getting stronger in my car.
I can't figure out where it is coming from. Plugs are tight. No spillage on tranny or diff. Everything is working fine.
Thinking I need to change the oil again.
Any experience with this out there?

Jedi54

iTrader: (7)

Redline FTW

Nubo

I've seen some claims that GL-5 can possibly accelerate wear on "yellow metals" in the tranny, such as brass alloys in the synchros. I've stuck with Redline MT90, which is is GL-4.

TeamRX8

iTrader: (25)

nevermind that Mazda says GL-4 and GL-5 are acceptable in the RX-8 Manual Trans Repair Manual

fwiw, that applied back in the 1960's, but no more

swoope

iTrader: (5)

and your kill me.

i bet your owners manual is a 04.. who knows what is out there now..

beers

TeamRX8

iTrader: (25)

not owners manual nor the standard service manual

MANUAL TRANSMISSION SERVICE MANUAL i.e. for rebuilding the 6 speed Aisin transmission

it isn't model year dependent

nycgps

iTrader: (1)

Its the same Transmission for all years.

and I think recently they changed the spec on what 07 or something to GL4 only. not 100% sure on that but I think so.

Im using MT-90 atm ... people said shift quality suck *** with MT-90 but it feels fine to me ... The tranny feels *tight* now, if thats what people call *shitty quality*

Nubo

You may be right. I've seen arguments both ways, and not just specific to the Aisin unit. Haven't seen anything that I would call conclusive in this debate so I err on the side of caution.

Since Redline MT-90 is the specified weight, Gl-4, and widely respected MT lube, it satisfies both Mazda's requirements and any doubts.

My observation after switching out the factory lube at about 12,000 miles was that the MT90 was somewhat more "sluggish", mostly when cold. But you quickly learn to slow the shift just a little bit, and then it feels very good.

Since the gear-lube selection at most parts stores is often sparse indeed, it's just as easy for me to purchase Redline via web as anything else. It works well for me. Redline gear lube was also a favorite of Miata owners for many years so there's a good bit of history with its use in this Aisin transmission.

w0rm

Getting crappier shifts after changing to MT-90. 5th gear synchos grind/slip going in, 6th as well at high speed. Never had a problem before, started happening immediately after the swap.

Thinking about swapping out to RP, any other suggestions?

nycgps

iTrader: (1)

Some people use BG stuff. not sure about that. heard its good.

I had RP for about 35K miles. well the tranny noise is getting worst. so I swap to MT-90. Shifting quality actually feels better, maybe I like the *tighter* feel. No grinding, less noise. so its good.

The longest user here I think is Expo, he use MT-90 and with over 100K his tranny still works fine.

Not saying RP is bad, but I think no one ever got over 100K with RP in their tranny.

Jedi54

iTrader: (7)

I had issues with RP, so far so good with the new transmission and Redline.

StixandStones

Well I found another thread that talked about gear oil odor.
I think that's what I searched.
Seems folks have had the same odor problem regardless of what they were using for lube.

Now, I don't know if I'm just getting nervous about the RP after reading your posts here or not. I might be getting more whine than before but the shifting is still great. I have trouble believing it has gone into reverse it is so easy.

The only shift problem I have is a short grind into 3rd at ~8500 rpm.
Might be I'm just a little too quick on the clutch work.

I suppose I should be covered by warranty since I used a lube grade that was called for in the manual (I have a 2004).

And....please excuse my ignorance. What do "FTW" and "fwiw" mean?
I don't go on many boards and I'm probably older than most you guys.

Jedi54

iTrader: (7)

FTW = For the Win !
FWIW = For what it's worth.

Nubo

This car is a funny animal. Sometimes I get the feeling that all the parts must be hand-made, judging from the huge variability of gas mileage, and then stuff like this where one gear lube works great in one car, but not another. I guess you've just got to find the one that your car agrees with

FWIW, I did have to modify my shifting habits a bit after switching to Redline. Have to be just slightly slower. It's almost imperceptible but just that split-second of hesitation before sending it home lets the synchros do their magic.

LionZoo

Check boot contamination.

Razz1

Language of the Starship troopers.