Best T-56 atf?

[swami]

hi all,
i have a 2003 cobra with the t-56 6speed and it is hard to shift. i have 7800 miles with the factory fill and i was thinking of trying mobil1 atf because i get readily get it down the street at autozone. redline says to use D4ATF but it causes the carbon fiber synchronizer seals to swell and shift even harder. i used redline D4ATF in a ,99 GT with a T-5 from 40,000 to 80,000 miles and i had a input shaft bearing noise develop around 60,000. tremec recommends dexronIII without any gear ratings in their T-5 and T-56. one tremec rep said to use mobil1 at svtperformance.com but another rep from their website said ford had stiff shifting problems with mobil1 in 2001. (ford didn't use the t-56 until 2003 so who do i believe!)i also put redline 75w90 with built-in friction modifier for the limited slip at 60,000 and no metal shavings when i drained the factory fill. at 82,000 i had a noisy rearend full of metal shavings and i ended up ovehauling and replacing every bearing so i'll never use redline again. i was thinking about royal purple. any knowledgeable responses are welcome. TIA

 

[mechtech]

Specialty Formulation's Synchroglide.
ATF isn't in the same ballpark.

 

[Idrinkmotoroil]

I've always wondered why such high hp applications use atf fluids in the tranny. Can't you use a thicker fluid such as Syncromesh or any of it's variants, including Amsoil MTF ?

 

[swami]

gm synchromesh is recommended by tremec for the t-3550 6speed used in the corvette and camaro. some of the guys use it over at svoperformance and swear by it but i am leery of using an unrecommended product.

 

[Ryan00TJ]

Nice car BTW! I love the 03 Cobra's and i'm on the darkside w my 02 LS1 SS Camaro. Basic Heads & Cam setup, 420rwhp. Any mods on your Cobra?

I made the mistake of using Redline's D4 ATF in my T56 and last November my tranny locked up in neutral while going down the track. I hit third gear at 6500rpms and it just didn't feel right. It did not grind going into gear and I was not powershifting either. Upon bringing the shifter out of 3rd gear it locked up in the neutral position. When my Father and I tore the T56 apart we found nothing wrong. To this day I cannot figure out what happened. We threw in a steel 3-4 shiftfork and upgraded keys and synchros and put it back together. Shifts fine to this day. Very crisp and smooth as from the factory. Rebuilding a manual T56 was pretty intimidating when you've never done any tranny work. I ran it through the gears on jackstands and drained the conventional DEX 3 out 3-4 flushes and refilled w M1 Syn ATF. I have no problems with the M1 ATF so far. Shifts smooth and I have not had any problems.

Alot of LS1 owners and T56 owners in general use the following with good results.....

Royal Purple Synchromax MTF
Amsoil's new MTF
GM Synchromesh

I might give Specialty Formation's new MTF a try here when change time comes around.

 

[mechtech]

Synchromesh fluids aren't THAT much thicker than ATFs. Just a little.
It's the add packs that are way superior.

 

[1 FMF]

read the threads at ls2.com/forums
Can I run a synthetic fluid in my T-56? Maybe. Look inside


I have an 02 camaro, been running pennzoil synchromesh for last 11000 miles since last December. I've tried everything, including redline d4atf, MTL, redline hi-temp atf, and royal purple synchromax along with cheapo atf's. Synchromesh is buy far the best and is also priced the best. It does better in cold weather than atf, and I've driven my car in 10F weather.
I also was in contact with a guy at ls2.com who had a '98 camaro with a t56 who was using synchromesh for at least 15k miles with no problems. I've called tremec (ttcautomotive) and they told me sometime in 1999 they upgraded the synchonizers to a more durable material, steel vs paper backed, not sure if the paper backed was carbon fiber or not. There's a lot of b.s. and inaccurate info all over the place concerning this, the guy at ls2 who stripped his t56 down and has pictures of it, is probably the most correct. The older style sycnhro's are believed to be paper or fiber lined and when using synthetics they either cause this material to deteriorate quicker, or the synthetic oil has a tendency to absorb water and the moisture is what causes the synchro material to "swell". How true this is I can't say, I don't have 1st hand experience.
Bottom line is, high horsepower + hard driving = short tranny life and lousy shifting no matter what the fluid. Top that off with a tranny made south of the border, don't expect it to shift like a honda.

I've run RP synchromax and would occasionally get a synchro zing noise when shifting at low rpm, and once hot the tranny seemed more noisy. It did shift well in cold weather, but in general I thought it performed worse than atf, shifting was still notchy especially when hot.

Redline hi-temp atf, which is just thicker, shifted horribly. definitely do not use it, waste of money.

Redline mtl, does ok when first filled but gets notchy after a few thousand miles I thought. I didn't refill with that because it's too pricy so I went back to syncromesh. I'm not a big redline fan anymore.