Mappinsj

look, I just want to know what the forum thinks about this fluid in t56 since there is no reliable recent source that explicitly states what fluid is called for



Mobile 1 synthetic automatic transmission fluid

calhoon

iTrader: (6)

That is the manufacturer's choice.

chrysler kid

iTrader: (14)

Any dexron3 atf is more than acceptable.

BALLSS

I would just use whatever the sticker next to the fill plug on tranny says or what is listed in owners manual.

If those say a synthetic ATF than the Mobil 1 is good stuff

I recall Tremac started using the carbon blocker rings in T56 99 or 2000. Previous was paper blocker rings and synthetics did not get along with those.

RevGTO

iTrader: (12)

https://ls1tech.com/forums/manual-tr...ghlight=Tremec

I concur with advice from Tremec tech support in the thread. I got some grinding on cold mornings when I replaced the original fill with Mobil 1 synthetic. Got better after switching back to Dex III.

Mappinsj

I have a carbon ring blocker kit. I was told paper doesn't like syn and carbon does

Darth_V8r

iTrader: (4)

Mappy my tranny was built by RPM. They said to use royal purple synchromax or AMSoil torquedrive.

whatsa347

iTrader: (6)

I just put penzoil synchromesh in mine, shifts like butter now.

Mappinsj

It seems that M1 syn ATF is good for carbon ring blockers, (which my car has), and not paper. I think I am gonna go ahead and get this stuff.

Mappinsj

After researching this for hours (simply because I want the right stuff)
I have come to the conclusion that Dextron VI is not the same as Dextron III and Tremec on their website FAQ recommends Dextron III for all their transmissions save the TKO 5 speed.

I have found that they actually recommend AGAINST all synthetic fluid


I will be buying Dex III for my t56 as it is still for sale separate from Dex VI.

chrysler kid

iTrader: (14)

Dexron III is the best fluid to use.

AAIIIC

iTrader: (19)

Is that the special Alabama formulation?

Mappinsj

hahahaha i was made when I was typing it, they took my link down I was using for reference because it was wrong website. Its fair though lol

Firebrian

I've done this "what fluid" drill twice in the past 5 years and keep coming back to Dex 3. And since I have paper lined friction rings, I stick with conventional fluids. Currently using the GM Man Trans Lube 88861800, which is a beefed up ATF with slightly more anti-wear chemicals than base line conventionals. That's a good choice in your car too, even if it shears down fairly quick. I just change mine every 4K miles to ensure it stays above the 6.4 cSt range. It's a factory fill in many older Corvette T56's and meant for life. Hard to believe that as it probably shears down under 5.0 cSt by 20K-100K miles.

https://ls1tech.com/forums/manual-tr...56-others.html ....my 2 cents from 2016.

The other synthetic ATFs (Amsoil ATD, Redline D4, M1 ATF, RP Synchromax, Honda D1) are good choices too. And they don't shear near as much as conventionals. The Pennzoil synchromesh is a notch higher in protection as it's a true GL4 manual trans lubricant with visc around 9.3 cSt. That ATFs are around 7.1-7.6. Though note that synchro ring operation is directly affected by viscosity. If I had the carbon rings in my car I'd probably try some of those synthetic ATF's as they have beefier add packs than the GM MTL ATF. You will find numerous threads on the internet of people having great results with all these fluids. You will also find people having negative results with all of them, except the conventional Dex 3's. The Dex 6's tend to be around a 6.0 cSt viscosity. Valvoline Max Life ATF has a solid add pack and doesn't shear hardly at all, but viscosity is 5.9 new. Too low imo and GM cautions against using it in any car they specced for manual transmission fluid.

RevGTO

iTrader: (12)

I bought my first M6 T/A with about 80k. It was shifting just fine, but I promptly changed out the factory fill to M1 ATF and started getting the 2nd gear cold grind. Switched back to Dex III and it got better, but it never seemed to shift quite as smoothly as it did before I changed it.

My current M6 has 91k and I'm sure is on the factory fill. It shifts like a hot knife through butter. Common sense tells me that the fluid must be sheared down, but based on previous experience, I'm scared to change it. Maybe it's like an old automatic where the sludge is holding it together, lol. If it ain't broke, don't fix it?

Firebrian

I can only say that when I bought my car in 2012 it still had factory fill in it though only on 12,000 miles. I changed it just due to age and not knowing for sure what condition it was in. It shifted just fine too. It looked fine coming out. Put regular Valvoline Dex 3 in and there was almost zero difference in shift quality. Though I felt it was maybe 10% improved? That could have been the Placebo affect too. But it surely was not worse. Changed it again 4 years later and no difference with the new stuff.

One advantage to getting the factory fill out is to remove whatever metal wear/break-in particles might be swimming around in your fluid. At 91K I'd take the risk and change it with GM factory approved MTL/Dex 3.