willians.pinho

hello

Why does manual transmission corvette use automatic fluid?

I can use this fluid for manual transmission?

https://www.motul.com/us/en-US/produ...r-300-ls-75w90

motul gear 300 ls 75w 90

irok

why not use the correct GM Dexron VI automatic transmission fluid?Thats what it was designed to run with

MARSC6

Do some research on what is involved in swapping the transmission first. Then maybe you will use the correct fluid.

dmk0210

Dexron III for the manual. ( GM #88861800 in the U.S. (#88861801 in Canada))

VI is for the automatic only. GM has specifically said that VI is not backwards compatible for this application.


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BlindSpot

I'm going to take a wild stab here, I think the OP is in Europe. He is stuck with limited options

Tremec manuals use fiber lined synchros. These composites are very fussy with the way they absorb fluid and perform. The wrong fluid and they won't absorb correctly according to design and can stick. Once they go dry they can/will burn.

dmk0210

Why would you want to use gear oil? Motul makes a Dexron III.

A lot of guys run Redline or Amsoil as well.


ATF in a manual trans is not unheard of. Tremec spec'd it for good reason. Do some searching and you'll see some reasons why.

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dmk0210

OP, search this forum (I'd search Tech and Z06 as well) for the word Dexron.

I've seen threads where alternative fluids are discussed in detail.

AORoads

Better yet, IF you are from a foreign land, write directly to Tremec and ask them what is compatible from your country of origin with their transmission. What you do not want to do is screw up your trans, and you will if you just pick fluids off the shelf because they sound compatible (but are not).

BlindSpot

I absolutely.....

CadVette

Automatic transmission fluid has been used in Tremec manuals for a long time. Do not use gear oil, only Dextron III is recommended due to the syncros.

BlindSpot

Twice now.....better make it Dexron.

1500cc

You probably want to spell it correctly if you're going to search for it ... there's no T in Dexron.

CMY SIX

BG products Syncro-shift II you will not believe how quite the car gets, none of them answered your question, but I will, the thinner ATF gets better fuel mileage that's why it's in there, if Motul says it's ok I'd tend to believe them, I've been using the BG stuff for 50.000 miles

WW7

Many cars and trucks have been using auto trans fluid in their manuals for years.. My 94 Ford F150 used it in the 4 speed manual overdrive trans..It's nothing new....WW

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dmk0210

Blindspot answered that question above.

Tremec did not specify ATF due to fuel economy concerns. It is due to compatibility with the materials in the transmission.

You may not have to use GM fluid, but you do have to use Dexron III compatible ATF.

dmk0210

My Jeep and Bronco used it in the transfer cases as well.

Dano523

Go to my post in the below and pay attention at 10:45 to the you tube video I posted.
https://www.corvetteforum.com/forums...ssion-ppl.html

Hence T56/Tr6060 syncro's use friction pads that the fluid has to clear and allow the pads to bite to the two surfaces and engagement, or you run into problems.

The days of old thick fluid for solid metal against metal type syncro's (and having to double clutch when they did not bite together) are long gone.

Same goes for the diff as well with the correct fluid, since you have clutch packs in it for the LSD.


Hence too much slip agent/lube to slipery and the LSD is not going to lock up correctly (thick peg leg burn out, or peg leg tire spin as you are coming hard out of a corner). too thin of fluid or not enough slip agent, and the clutch packs will stay locked up to turn the diff into a spooled diff instead (read tire wear since the inside rear tire will be turning as fast as the outside time as you try to go around a corner slowly and spin the inside tire).

BlindSpot

Good info Dano and what I was conveying in post #5. I've rebuilt Tremecs. The rebuild kits come with instructions and there are seriously bolded notices regarding soaking the fiber synchros (blocking rings) over night and in the proper fluid; otherwise, brand new synchros could be destroyed on startup. Even the old ones, if new ones are not used, need to be soaked. And same with the Diff and the clutchpacks (similar fiber mat'ls). This is the reason for the crazy figure 8s when changing oil in the diff, BC the clutch packs go dry even if taken out of a fluid bath for a short time.

This is why I shake my head when so many find themselves caught up in marketing hype and changing the gear formula with some aftermarket products. Such a BIG gamble some take, and for no real technical reason. These are not big clunky steel gear boxes like they were in the old days.

One other point, although it was a warning on an older Tremec I rebuilt, NOT to use synthetic fluid because there were compounds in synthetics that acted too aggressively on these fiber pads. And another reason you see Dexron III, but warnings against using newer, more advanced formulas of Dexron.

And this is THE REAL REASON these transmissions use auto trans fluid.

cclive

Dex III not VI.