GM Synchromesh.....would like to hear from those that are using it. Is it safe for the synchro's in my 98 Vette? I know it's a partially- synthetic fluid.
GM Synchromesh
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it's safe, yes. i can't understand why GM doesn't specify it for the T-56, but it's long been known in racer circles. i know of T-56s running it since the mid '90s.
one thing to note, though... the hot knife through butter shift feel goes away after some abuse. maybe whatever additive is responsible for supplying the proper synchronizer friction is easily burned off, i don't know. (from my limited chemical knowledge, kerosene appears to be an active ingredient.)
redline mtl behaves exactly the same way.
i use the synchromesh in both my camaro and my vette (ZF6), but i change the fluid every year.
when royal purple synchromax became available, i recognized it as a competitor to synchromesh and mtl. (at least as far as marketing goes.) i used it in my vette.
after 2-3 months (and only a few auto-xes), the shifting became difficult and notchy. i decided to drain the fluid and go back to synchromesh. i found a lot of visibly large brass particles when draining. this never happened before with other fluids, and hasn't happened since sticking to synchromesh. and, the shifting went about back to normal with the syncromesh.
not any kind of scientific observation, but it made me doubt the RP product enough to spread the word.
-michael
Thanks for sharing, Michael. Stories such as yours (that last bit) are not new to me.
Ever try the Pennzoil synchromesh fluid? I wish they would specify what weight it was.
Personally, I've been an MTL fan since all my apps (Hondas) Have called for a 10W30 motor oil and I've never found it lacking ... even after 50,000 miles.
--- Bror Jace
Ever try the Pennzoil synchromesh fluid? I wish they would specify what weight it was.
Personally, I've been an MTL fan since all my apps (Hondas) Have called for a 10W30 motor oil and I've never found it lacking ... even after 50,000 miles.
--- Bror Jace
Thank you michael...I guess you said what I needed to hear. I will take youe advice about losing "something" in the shifting dept.after a period of time. I can deal with changing it once a year as you do. Thanks for the input. Bob
Hello, I'm new to this whole subject so go easy on me if I'm not as technical as most people. I have been using Redline MT-90 in my 2001 Celica GT-S tranny (C-60 tranny) and it has been working fine. It is coming time for my tranny fluid to be changed and was wondering if this GM synchromesh would be safe for my transmision. My current fluid teh redline MT-90 is a GL-4 fluid and I was told to only use GL-4 fluids in my transmission as GL-5 fluids would ruin the brass (or bronze, can't remember which) syncros in my transmission (the reason I didn't buy Redline 75w-90NS). Would the GM Synchromesh be safe in mt transmission? Which gear oil do you suggest I use?
Thank You
Thank You
Redline MT-90 is a GL-4 and has been working great in your transmission. Why do you want to try something different that may not work good and may harm the synchros? I'd stay with Redline. FYI, I use MT-90 in my Muncie 4-speed and found that it improved shifting compared to regular gear oil. I have used a GL-4 oil that NAPA sells (Sta-Lube) and that also worked good.
scrub, i believe the syncromesh is probably too thin for your application. it tends to be used in transmissions that might otherwise specify ATF or engine oil.
bror, never tried the pennzoil stuff. it's comparable?
-michael
bror, never tried the pennzoil stuff. it's comparable?
-michael
I agree. If it ain't broke, don't fix it. Why would you want to use an OEM oil from a different manufacturer when you already have something which works great?
I am rarely impressed by OEM oils ... especially when cost is factored into the equation.
Pennzoil's specifics on this fluid aren't too clear to me. They don't even state an actual weight anywhere on the bottle or their site.
Their technical fact sheet:
http://www.pennzoil.com/penn/products/car_truck/pdfs/gearoil/SynchromeshFluid.pdf
It looks like the thin side of a 30 weight oil (if that) at temperature.
--- Bror Jace
I am rarely impressed by OEM oils ... especially when cost is factored into the equation.
Pennzoil's specifics on this fluid aren't too clear to me. They don't even state an actual weight anywhere on the bottle or their site.
Their technical fact sheet:
http://www.pennzoil.com/penn/products/car_truck/pdfs/gearoil/SynchromeshFluid.pdf
It looks like the thin side of a 30 weight oil (if that) at temperature.
--- Bror Jace
Ok then, I should stick with my MT-90? it's true that I don't have any problems with the Redline now, but I want to do the best preventative maintinance I can. Are there any other fluids that I shoudl ook at other than MT-90?
Thank You
Thank You
00 Scrub, if you are set on trying something different, give BG Syncroshift a look ... or the comparable Motul fluid.
Sourcing these will take a bit of work, however, and each is at least as pricey as Red Line.
--- Bror Jace
Sourcing these will take a bit of work, however, and each is at least as pricey as Red Line.
--- Bror Jace
Be careful,there are different friction modifier variations of synchromesh.The Synchromesh used in high performance applications is standard Synchromesh,Part # 12345349.
I should inform you that this is the U.S. Part number...the Canadian part # is 10953465.
I thought there was some question on this fluid from the manufacturer of the tranny with regards to the graphic washers.
Vettenuts...You just lost me. What did you mean by the "graphic washers?" I just put this fluid in my tranny....shifts pretty nice, but if it's not good for the tranny, I'll take it back out and try something else...What do you use?
Hmm. Ok I'll give the BM and Motul a look. Thanks for the heads up. Does anyone know which part number GM Synchromesh I would need for the proper firction modifiers or will I not be able to find it. The Redline is nice, I was just wondering if there was anything better.
oh, right, sorry, i should have mentioned that.
that's absolutely correct, the synchromesh we're talking about is #12345349.
-michael
Sorry, typing fast and did it from memory!!
I had found this quote on another board, supposedly from Tremac: "Our recommended oil for the Z06 transmission is Dexron III. We feel that if you wanted to use the GM Synchromesh, we do not see an issue but have not done any testing for this. I do not know the GM Synchromesh would impact the carbon rings in the synchronizers."
Based on this I was undecided on what to do, however everyone who has used it states it improves the shift quality dramatically. The only negative I have seen to date is those hard core Autoxers have found that the oil loses it's shifting quality when run hard and heated.
I have a 2000 Firebird with a T56. I changed the factory fill at around 2K miles to Mobil 1 Syn. ATF. Did not like the Mobil 1 ATF and changed to the Syncromesh on the recomendtion of a friend at around the 10K mark.
I like it better than the Dextron or the Mobil 1. BTW, the local dealership mechanic told me it was a bad idea. Only Dextron would do. Part of me thought it was just dealership propaganda, part of me worried a bit. I called a GM customer service number and asked them. They said it would be OK. I tried it and as I said, I like it. Been in for about 25K miles now.
The only thing negative that I've noticed about it is that it seems a bit more notchy than the Dextron on cold morning. Once warmed up, it feels better than the Dextron. It is much better than the Mobil 1.
I like it better than the Dextron or the Mobil 1. BTW, the local dealership mechanic told me it was a bad idea. Only Dextron would do. Part of me thought it was just dealership propaganda, part of me worried a bit. I called a GM customer service number and asked them. They said it would be OK. I tried it and as I said, I like it. Been in for about 25K miles now.
The only thing negative that I've noticed about it is that it seems a bit more notchy than the Dextron on cold morning. Once warmed up, it feels better than the Dextron. It is much better than the Mobil 1.
A well respected C5 Corvette mechanic said:
"NEVER, under any circumstances, should the GM syncromesh fluid be used in the T56. It is engineered to work in New Venture, and Isuzu manual transmissions, and nothing more. Installation of this fluid will clog synchronizer rings, and create reliability problems."
I take it from what I am seeing here that this is simply not true?
"NEVER, under any circumstances, should the GM syncromesh fluid be used in the T56. It is engineered to work in New Venture, and Isuzu manual transmissions, and nothing more. Installation of this fluid will clog synchronizer rings, and create reliability problems."
I take it from what I am seeing here that this is simply not true?
Hey 1 FMF-
Thanks very much for the reply. Amazing how something that you would think is simple seems to get so complicated! Anyhow, the GM guy I referred to is c4c5specialist over on C5Forum.com - generally knows his stuff and is very helpful.
Anyhow, the heck with it. I'm wore out. I'm going to switch from the Redline D4 ATF (I'm not much impressed either) to the Synchromesh I (#12345349) and see how it goes. I will check the fluid after a while just to see if there is any crud in it.
Thanks very much for the reply. Amazing how something that you would think is simple seems to get so complicated! Anyhow, the GM guy I referred to is c4c5specialist over on C5Forum.com - generally knows his stuff and is very helpful.
Anyhow, the heck with it. I'm wore out. I'm going to switch from the Redline D4 ATF (I'm not much impressed either) to the Synchromesh I (#12345349) and see how it goes. I will check the fluid after a while just to see if there is any crud in it.
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