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will this trans fluid work, or will it eat my syncros?

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AlphaAssault

15+ Year Contributor
480
1
Sep 5, 2007
Tyler, Texas
i bought some store brand transmission fluid that was an "80w-85w-95w" weight fluid. it is not synthetic. the bottle said that it was suitable for both GL-4 AND GL-5 rated applications. i think stock weight is 75w-90, so this is a little heavier. will this fluid work in my transmission, or am i playing with fire?
 
Ive used that before but, i found some amsoil and it works great. Plus its only a few dollars more, 12 dollars at a auto store here in town.
 
im more concerned about the syncros. will this fluid eat them or not?
It is my understanding that any GL5 gear oil will be corrosive to the brass synchro rings.

I wouldn't chance it....not when there are so many companies out there that make trans oil that is safe for our cars.

By being rated a GL5 oil, it means that the oil in the bottle exceeds the requirements for all gearboxes that previously used GL4. What they forgot to print on the bottles is that it's not for use in gearboxes with brass synchros.

The same thing is happening right now with the "SM" motor oils. The "SM" is supposed to meet or exceed all requirements for anything below it....but what they didn't realize is that by taking the ZINC out of the oil, it now ruins camshafts in engines with flat tappet cams. The flat tappet cam engines are about as rare as our brass synchro trannies these days.
 
Syncromesh is whats in there right now, and it is NOT doin it for me. its too thin, its not slowing things down fast enough, so shifting is excessively notchy. im not going with syncromesh again, im looking for something different; something thicker.

just so im understanding, this generic mineral oil that states "meets or exceeds gl4 and gl5 requirements" WILL destroy my syncros? the place also had some royal purple 75w90 synthetic trans fluid that was gl4 and gl5 approved as well, would that synthetic fluid eat my syncros also?
 
GL-5 fluids contains sulpher which eats on the brass and bronze of the syncros - why it's in rear end differentials and considered a gear oil. Plus, GL-5 is too slippery and will not adhere to the gears in the tranny very well-doesn't have the shear tension as does GL-4 fluids have.

this generic mineral oil
The key word here is "generic" which usually means fluids that was rejected by Quality Control and packaged for worn out trannies, or trannies that needs filled to get by. I'd trash it, and get the synthetic of your choice.

Personally, I've got Redline MT-90 in my tranny which was the best I've encountered in my tranny with many, many 10K miles on it.
 
any BRAND with GL4 and 75-90 W will work fine in DSM trannies

however if you have 95 w which is a bit heavier i dont think this should harm anything ( correct me if i am wrong)



again any brand would work if it has GL4 spec and 75-90 w

good luck
 
GL-5 fluids contains sulpher which eats on the brass and bronze of the syncros - why it's in rear end differentials and considered a gear oil. Plus, GL-5 is too slippery and will not adhere to the gears in the tranny very well-doesn't have the shear tension as does GL-4 fluids have.

The key word here is "generic" which usually means fluids that was rejected by Quality Control and packaged for worn out trannies, or trannies that needs filled to get by. I'd trash it, and get the synthetic of your choice.

Personally, I've got Redline MT-90 in my tranny which was the best I've encountered in my tranny with many, many 10K miles on it.

the synthetic of my choice would be either royal purple max gear 75w90 synthetic trans fluid, or royal purple syncromax synthetic trans fluid. thing is, both those state as well "meet or exceeds gl4 and gl5 standards" or something to that effect, which is exactly what the mineral oil said. i think ill just call the mineral oil people tomorrow and ask them if theyr fluid is safe for brass syncros. that should give me a pretty definite answer. whats the difference between the RP max gear and the syncromax anyway?

well there isnt an email address or phone number on the bottle of fluid im wondering about, so that sucks. the exact wording on this fluid that has me curious about its application in our vehicles is: "API Services GL-5, GL-4". thats all it says about its compatibility. the name of the stuff is 'Parts Master SAE 80w-85w-90 Gear Oil.' not a whole lot of info here.
 
I use 2/3 pennzoil syncromesh (available at autozone) and 1/3 redline shockproof heavy (available at summit, jegs or extreme psi).
 
I've read several threads on this same subject, hearing many different opinions. The link posted above seemed to say syncromesh is fine for low power applications. By "low power", does he mean any 420a? I would hate myself if I wrecked the synchros. Keep in mind my eclipse is NA. I've already looked for syncromesh at advance auto and they don't carry it, so I will have to order it. What whould I get?

[Read the post directly above this one.]
 
We are running Lucas syn for our tranny and rear-end on a 450hp + and so far loving it.
 
What is this 2/3 pensoil mixed with a shot of mt-90, and add a dash of yadda yadda? We arent mixing drinks...

Transmission fluids are not designed to be mixed with other tranny fluids. Why not just use one? Synchromesh is too thin, which led to the destruction of my first tranny. So I now use Redline mt-90 with my new TRE tranny. Jon said that Syncromesh is far too thin, and causes increased gear wear. Yes, it does make trannies shift better, because syncros like thinner fluid. He did say that syncromesh is alright for stock DSMs, but we dont have stock cars.

Save the mixing for your girlfriends drinks, go with Redline MT-90, or MTL.:dsm:
 
i thought i read somewhere that is the trans fluid says GL-5 anywhere on the bottle, that it is unsuitable for our transmissions.

Also, i emailed Jon at TRE, and he said that the 90's have fiber lined syncros, and that I should be using non-synthetic fluids in this trans. why have i never read that before? with all the trans fluid topics on this site, it seems like this info would be kind of important. anyone have anything else to say about synthetic fluids in a 90 trans?
 
From Jack's Transmissions - www.jackstransmissions.com ..

Q: What kind of gear oil do you recommend?

A: For our DSM and 3S transmission rebuilds we recommend factory Mitsubishi 6-speed manual transmission gear oil from the 2005 Mitsubishi EVO MR. (Part number mz313376). This is the best oil to use as it has the perfect blend of friction modifiers to keep the tranny shifting smoothly and prevent gear failure. Please make sure you use the proper amount as specified in your owners manual (typically 2.4 Qts.) Gear oil choice is very important and varies based on preloads and synchro blocker ring design, therefore it is strongly recommended that you stick with this fluid for our transmissions. If you are unable to locate Mitsubishi MR 6-speed oil from the Mitsubishi dealer, Redline Heavyweight Shockproof 50/50 mixed with Valvoline 80W-90 gear oil will also work just as well. For transfer cases and rear ends, use Redline Heavyweight Shockproof ONLY. It is especially important to use only Redline Heavyweight Shockproof fluid or Mitsubishi dealer t-case fluid in EVO transfer cases. DO NOT use Synchromesh, BG Synchroshift I or II, or Royal Purple. These fluids will destroy synchros and gears and void your warranty! THESE ARE THE ONLY FLUIDS WE HAVE EXPERIENCE WITH. If you ask us "Will xyz fluid be okay?" we won't have an answer for you.

So, it's sorta which oil filter, air filter, spark plugs, TV dinners, steaks, potatos, movies, et.al. ..that you like - all personal preference.. no winners and losers here.

-DSM
 
I've already looked for syncromesh at advance auto and they don't carry it, so I will have to order it. What whould I get?

[Read the post directly above this one.]


Advance auto doesnt carry it, you have to go to AUTOZONE, they always have it $6.49 a quart :thumb:
 
You missed the point. He has an N/T. It must run factory transmission fluid only, or the synchronizer brake material will be destroyed.

As for the mixmasters out there, it's always iffy to combine greases. Some of them will cause others to lose their emulsification, and I've never seen a listing of whose works with whose. Pick a lube and stick with it.

No matter what you choose, you're still dealing with an economical street transmission shifting through cables. It'll never feel like a Miata gearbox.
 
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