I dont see any polls for what kinda gear oil everyone prefers for Transmission and Differential. So here it is. I know a lot of you guys argue back and forth on whats better so now we will find out! Im not referring to whats best for race prep cars, just the daily driver/sprited driving community!

DO NOT use royal purple maxgear in you're tranny.

I switched from OEM tranny fluid to RP maxgear and I started getting 2nd gear grind. I switched to Red Line MT90 and the grind was gone after 2days.

i'm sticking with OEM after needing a transmission replacement from maxgear...

haha im in the SAME boat as both of you... i guess we will see.....

royal purple is that bad?? i used it and it made my car that was grinding shift better?... maybe thats why it finally died.. lol

RP has worked perfectly fine for me for more than 50K and more than 1K of track miles.

I'm using RP Maxgear. I started off putting the 75W90 in the tranny and rear end.

I started having problems putting it in gear especially after a run in autocross. I switched to RP 85W140 and the feel is perfect. It even goes into reverse now when its cold outside on the first try. I still have the 75W90 in the differential though. I'm thinking about maybe getting the KAAZ gear oil or replacing it with something thicker.

When I was using the lighter RP it never would grind, just would not go into gear. It did make a whiiirr noise though. Maybe no one should put 75W90 in their transmission.

I believe Red Line is GL-4, which is better for transmissions that contain brass parts. My first fluid change was to Royal Purple. Would make a noise when shifting to 5th gear. Changed to Red Line, and the noise went away after a few days.

I used RP on my first transmission.
Now using Redline with the new transmission.

You decide... ;)

redline 75w140ns

lol looks like i have some rp tranny fluid for sale! anyone?? ill still use in my differential though

ok which to get redline 75 90 or 75 140 im going to order some right now if you guys can tell me which to get

OEM gave me the best shift quality and I've tried both Royal Purple and Redline. If I could find the OEM again I'd put that in.

Shell Transaxle Oil, 75w90.
Not very commercial but is used as the differential lube in the ferrari challenge.
Put it both in my shift and my differential while mounting the final gear.
It really changes the shift feeling and doesn't soften after 40minutes of continous track drive.
I really suggest it!

too late i just ordered redline 75W140NS GL-5

wrong choice

ok guys. i have a AT and i need to change the fluid. and im thinking about going with Red Line.. but what weight and that stuff should i get? and how much does the AT take?

I use redline

ok guys. i have a AT and i need to change the fluid. and im thinking about going with Red Line.. but what weight and that stuff should i get? and how much does the AT take?

I drive an M/T so I don't know what specs are recommended BUT the info is in the back of your owner's manual. Look under fluids in the index.
If you don't have the owner's manula, register on Mazdausa's website as an owner and you can download a PDF version. :)

wrong choice

How?....

What about BG syncroshift 2?

I'm using Redline for both. 75w90 weight in the tranny.

I really want to try this: http://www.fcsdchemicalsandlubricants.com/supplier/product.asp?product=Full%20Synthetic%20Manual%20Tr ansmission%20Fluid&category=Transmission%20Fluid

The 6 speed Miata guys seem to really like it, and as we all know our transmission is pretty similar to the 6 speed NB tranny.

I got some Amsoil 75w-90 GL-4, going to try to have it done this weekend. Probably gonna have them do a BG flush to get out the Maxgear. My 2nd wasn't great before, that's why I switched to Royal Purple, but then 2nd got worse and other gears started shifting bad at times.

I'll let you know how it goes.

How?....

You need GL-4 not GL-5.

The techs at Red Line said MT-90 for the tranny and 75w90 for the diff.

too late i just ordered redline 75W140NS GL-5

Don't use any Redline products with NS in the description. They lack modifiers.

RP max gear for me, so sar i feel better shifts, i don't double clutch the reverse any more, and feels real smooth... no grinding to report here...

BTW RP 5-20 in the engine too... no problems noted

I used to use RP for 38K miles. then my tranny starts having this *BOV* kind of noise when I clutch going faster than 30 mph.

Switched to Redline MT-90, noise disappeared after a week.

Im going to switch my rear diff to Redline's stuff later. Now its still using MaxGear.

RP max gear for me, so sar i feel better shifts, i don't double clutch the reverse any more, and feels real smooth... no grinding to report here..

lol. That's what we all reported the first few years. Then the car magically needs a new transmission.

Unfortunately I cannot just magically turn back the odometer miles. There are strong recommendations for Royal Purple Max Gear peppered all over rx8club, and if they are all wrong, everything I know is jeopardized.

Perhaps even Redline MT-90 is not without its share of problems. Maybe in another few years it will eat through the transmission covers.

It's possible as well that the suspicious noises went away simply due to fresh fluid, not from switching one brand to another.

We suspect, but cannot prove.

Maybe in a few years we'll report that pre-mix or any other rotarded behavior has unintended consequences on rx8.

Royal Purple Max Gear have been proven that it's not good for our transmissions. They lack special additives and modifiers that our transmission require. Hey, it's your transmission though, not mine. Feel free to use it.

Mobile 1 works.

Royal Purple Max Gear have been proven that it's not good for our transmissions. They lack special additives and modifiers that our transmission require. Hey, it's your transmission though, not mine. Feel free to use it.

Where exactly is the concrete proof? I see a lot of anecdotal evidence and some conjecture due to its ratings, but nothing that would qualify as scientific proof that the Royal Purple is bad for your transmission.

(Note, this doesn't mean the Royal Purple might not be bad, but I haven't seen what could constitute as proof.)

ran rp maxgear for 55k trouble free miles.. am going to b&g soon..

beers :beer:

Unfortunately I cannot just magically turn back the odometer miles. There are strong recommendations for Royal Purple Max Gear peppered all over rx8club, and if they are all wrong, everything I know is jeopardized.

Perhaps even Redline MT-90 is not without its share of problems. Maybe in another few years it will eat through the transmission covers.

It's possible as well that the suspicious noises went away simply due to fresh fluid, not from switching one brand to another.

We suspect, but cannot prove.

Maybe in a few years we'll report that pre-mix or any other rotarded behavior has unintended consequences on rx8.

I swapped transmission fluid once a year. Because maxgear was better feeling during cold starts, I kept it over redline. The last two fluid changes things were feeling rougher. With the most serious grinding issues taking place almost immediately after the last fluid swap. In fact, I did the last fluid swap ahead of schedule because the transmission was feeling notchy and crappy and I hoped new fluid would smoothen it out.

I do not need more proof than this. I ran maxgear for over 40k miles, half of which was turbocharged.

Where exactly is the concrete proof? I see a lot of anecdotal evidence and some conjecture due to its ratings, but nothing that would qualify as scientific proof that the Royal Purple is bad for your transmission.

(Note, this doesn't mean the Royal Purple might not be bad, but I haven't seen what could constitute as proof.)

Exactly. I think individual driving habits and our usage of the clutch pedal is by far the factor in transmission swaps. Seems a little pointless to blame RP for failed transmissions, when race teams have already commented time and time again to the weakness of the stock tranny under aggressive driving conditions.

I do not need more proof than this. I ran maxgear for over 40k miles, half of which was turbocharged.

How can you blame RP for failure, when you operated your car well outside of the parameters of the factory RX-8 with the turbo? Seems skewed from the information you've supplied.

How can you blame RP for failure, when you operated your car well outside of the parameters of the factory RX-8 with the turbo? Seems skewed from the information you've supplied.

The grinding started before the turbo was installed. It got worse as time went on. I do not drop the clutch or do anything funky with the transmission.

I don't care if anyone believes me, I'm just throwing in my 2 cents. I joined the crowd who swapped around fluids 4 years back and maxgear felt the best to me at the time. Initially it feels good for everyone, that's why so many used it.

The grinding started before the turbo was installed. It got worse as time went on. I do not drop the clutch or do anything funky with the transmission.

I don't care if anyone believes me, I'm just throwing in my 2 cents. I joined the crowd who swapped around fluids 4 years back and maxgear felt the best to me at the time. Initially it feels good for everyone, that's why so many used it.

It has nothing to do with believing you or not. You didn't state whether the issues began pre or post turbo so I was seeking clarification.

I'm actually thinking I'll switch to redline or some other at my next gear change simply to see if there is a difference. I've always used RP and my transmission has been fine. But I also can't say that it is smoother/better with it than with any other gear oil out there...

extra hot non-fat mocha with 2 extra shots of espresso

oh, and only clueless twits think there's anything wrong with GL-5 oil

too late i just ordered redline 75W140NS GL-5

don't listen to the book experts that have no direct experience, it's a perfect choice for your transmission.

The NS is actually what you want, the regular has modifiers for LS diffs and these can cause the synchros to have a harder time speeding/slowing. I used RP affter using Redline MT90 and within 5000 miles I had a constant 2nd gear grinding. Went back to MT90 and it was gone after 20 minutes of driving. You decide...

When I change again, I am going with a 75-90ns or 75-140ns Redline.

The NS is actually what you want, the regular has modifiers for LS diffs and these can cause the synchros to have a harder time speeding/slowing. I used RP affter using Redline MT90 and within 5000 miles I had a constant 2nd gear grinding. Went back to MT90 and it was gone after 20 minutes of driving. You decide...

When I change again, I am going with a 75-90ns or 75-140ns Redline.

Or just go for GL-4 Fluid :)

I changed out the stock fluid with Redline MT90 and 75W90 gear oil, it feels much better so far.

It is a challenge to keep up with the latest rx8club fads. It's almost a "rumor of the week" on what is "in" as far as "protecting" the rotary engine.

There should be a gauge on the club homepage that points to what weight of engine oil is currently in fashion, based on the number of positive comments for that specific weight type within the last 14 days.

All this conjecture is the only thing I have to base rx8 decisions off of. Yesterday I emptied transmission of MaxGear and pumped in the Redline MT90 just to silence the nagging psychological rumors.

It's all psychological but I can't stop myself from performing all these things. I'm not hurting anything, just spending money on ordering more washers from the Mazda parts counter, and spending some hours getting dirty.

OEM gave me the best shift quality and I've tried both Royal Purple and Redline. If I could find the OEM again I'd put that in.

on the same boat here buddy, and my ride is pretty new. any real THIN synthetic fluid that i used (RP) problems would start. i got the whole cold morning notchy shifting deal with it.

unfortunately... its hard as hell to find a GL-4 trans specific fluid. so i ran with some valvoline thicker gear oil with some left over RP in there. and put in a shit load of lucas oil stabilizer...

now being more careful with fluids, those GL-5 stuff doesn't perform well in the trans as it was meant to be in the diff with diff additive.

so yeah, i'd like to just find some thick conventional name brand GL-4 fluid for the trans if not able to find what they use for oem.

*note* new owners, don't even bother with the experiment! i've confirmed with other mazda owners/techs/roadster club members, the GL-5 specs fluids gives worst shift quality, new or old. whereas switching out with GL-4 spec rather name brand or not (like mag1 or some other CRC product) will not give any worst shift quality. or the thicker viscosity it is, the shift problems doesnt show up for some reason... even being a GL-5 spec fluid.

this is my experience and opinion... i find it useless to try the synthetics.
but the diff is another story.

user 24, we all like to help others to be more informed. but learning out for ourselfs is also something we all need to do before spreading rumors.

i thought this has been covered before, but i guess i'll cover it again.

there are NO added benefits with using RP for the trans. its a hybrid GL4/GL5 fluid, and will create cold fluid issues such as notchyness and possible shift grind before warm-up.

racing beats pride and recommendation of RP fluids may be different than our intended use as their car may always see extreme high temps and pressure during vehicle operation time. hence the reason why on my brand spanking new car and trans with RP fluids... is more notchy and has a higher tendency to want to grind during the cold morning temps anywhere under 60degrees.

i use to get these fluid specs mixed up myself as having to own 2-3 other RWD's w/o a lsd. i'd simply just get any ol GL4 gear oil that was cheap and available...
but NO, not the rx-8. its got a nice LSD and a premium trans with all the works, but is very sensitive.

so i guess my point is, choose wisely. and don't simply follow someone's recommendation of what they "think" is good. but try to learn the grades/ratings/ and match oem specs before doing anything, and you'll be clear of ANY problems.

we're all human. mistakes happens to even the best of us!
good luck on ur fluid choice.

TM

i want to change my gear box oil..
buti don't know..
where to buy it...
i leave in malaysia....
and how much?

I've tried Royal Purple MaxGear and Redline MT-90 in my tranny and the Redline shifts noticeably smoother than RP and the cold grinds go away really quick. So I recommend Redline over RP, at least in my NE climate.

As far as the diff goes, it seems fine, there's nothing weird/wrong with the rear diff, so I have no idea how to tell the difference vs stock vs RP vs Redline fluids.

I use Greddy Trust gear oil 75w90 GL6.
It's just perfect. Much smoother than the oem stuff and get's even better when warmed up.
What I would like to test though is Lubrication Engineers' Gear Oil, which I believe must be better than anything else.
P.S. I have a low power 5MT (EUDM) which I think has a gearbox from the older MX5 Miata. Gear-switching with this gearbox has always been very hard, so the difference with the Trust gear oil was very noticeable.

1 1/2 month later after switch from RP to RL, this is what I got.

Used to have RP Max Gear in transmission early on, within first few months. Then, ordered on-line MT90 and put into transmission when I considered these comments here. Now, the transmission has the famous noise when the clutch is out.

Seriously, the noise sounds like a pathetic robot. Like a kid's science project robot that has just run out of batteries and can't get back up over and over again. It's terrible!

So would you rather do RP MaxGear and have a smooth sounding transmission, or switch to MT90 and get some grinding noises, and surprisingly according to some theory it is MT90 that is supposed to be better for your transmission?

Now, the third option needs to gain some more momentum. 50/50 mixx RP/RL. That's going to be the new trend. You read it right here on rx8clubz. Several offshoots will be 75/25 mixx RP to RL, or 60/30 mixx RL to RP. Always topping off with 2% rotary magik, 4% rumors.

1 1/2 month later after switch from RP to RL, this is what I got.

Used to have RP Max Gear in transmission early on, within first few months. Then, ordered on-line MT90 and put into transmission when I considered these comments here. Now, the transmission has the famous noise when the clutch is out.

Seriously, the noise sounds like a pathetic robot. Like a kid's science project robot that has just run out of batteries and can't get back up over and over again. It's terrible!

So would you rather do RP MaxGear and have a smooth sounding transmission, or switch to MT90 and get some grinding noises, and surprisingly according to some theory it is MT90 that is supposed to be better for your transmission?

Now, the third option needs to gain some more momentum. 50/50 mixx RP/RL. That's going to be the new trend. You read it right here on rx8clubz.

the transmission makes noises when the clutch is released. This is a true statement for all our cars. It's how it works.

Maxgear is the wrong kind of fluid for the transmission. It's how I lost my transmission. It will not cause your transmission to die right away. In fact, your transmission will feel great. It will take years, like mine did, till your synchos start to show signs of wear and will grind as you try to shift.

What about

For Transmission:
Amsoil Synthetic Manual Transmission and Transaxle

For LSD:
Severe Gear 75W-90
Synthetic Gear Lube SAE 80W-90
Long Life Synthetic Gear Lube SAE 75W-90


Has any one tried these? What are your opinions?

http://www.amsoil.com/storefront/mtg.aspx
http://www.amsoil.com/storefront/svg.aspx
http://www.amsoil.com/storefront/fgr.aspx
http://www.amsoil.com/storefront/agl.aspx

I use amsoil GL4 in my new transmission.

http://www.rx8club.com/attachment.php?attachmentid=122543&d=1213934628

I just switched to Amsoil myself. Using the same stuff as Mysql for my transmission and Severe Gear 75w90 for differential.

So far impressions are good. The noise while the clutch is engaged and engine at idle is noticeably quieter, almost gone. The shifts feel good. Haven't tested it during cold weather considering it is summer and all, but it is easier to get into reverse and 1st gear before it is up to operating temp. Overall it is too early to really tell, but it seems like it is a pretty good choice and if it continues to perform like it has been for the past month I would definitely use it again.

I use MT-90 for tranny.

and Mixture of Maxgear & Mobil1 75w90 for rear diff. reason why was that cuz when they did my clutch last time I ran out of RP maxgear for rear diff. then they sell me a bottle of mobil1. so far so good, but I will switch it to Red Line 75w90 later this month.

okay so im on summit racings website trying to order my redline tranny/diff fluids but i dont know exactly which one to get i know i need 75w90 for the diff and mt90 for the tranny but do i get the shockproof or just the synthetic gear oil for the tranny?

Redline Here! Both in my tranny and rear end.

omg you have 666 post you unlucky bastard :P

redline ftw!

Has anyone had any trouble with RP in the rear diff? I've read lots of posts saying how RP lead to grinding problems in the transmission, but nothing particular to RP screwing up the rear diff. If anyone has any comments as to why using RP in the rear diff and RL in the transmission is not a good idea, please tell me before I screw something up! =) Thank you!

as far as i know RP is ok in the diff, but IF you have access to redline, use it !

I probably skewed the results as I'm sure a lot of you could care less about ATs, but I voted RP intending to cover their Max ATF product. It's good stuff.

I haven't done my differential yet. Not enough research to make a decision... it'll either be RP or RL... heck, I don't even know what grade to use at this point.

when i was going to change otu my OEM Transmission and Diff to RP, i did not because Yoshiya at the local shop here in OC said he just worked on a few transmission that failed and used RP... I choose Redling jsut to be safe for both and it is perfect for far.. i am ready to switch out again and probably will use redline again, was thinking about going back to OEM just in case, but i think Redlin GL4 is fine.

trans: Redline 75W140NS

diff: Kaaz 80W90 (with OE LSD)

okay so im on summit racings website trying to order my redline tranny/diff fluids but i dont know exactly which one to get i know i need 75w90 for the diff and mt90 for the tranny but do i get the shockproof or just the synthetic gear oil for the tranny?

get the synthetic, shockproof should be reserved for racing only because it needs to be changed often