T-56 fluid change - went old school with fluid.

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The Tremec T-56 in my CTS-V was in need of a fluid change. When I bought the car I noted that it was easiest shifting T-56 I have owned or driven (I've driven many). Though that positive feature has started to fade in the past year or so. Factory fill was DexIII but I did not buy it new.

There is endless indecision about what is "best" for a T-56, many positive and negative reviews for the same fluids. I have had two threads on here in the past while trying to figure out what fluid to go with to have smooth shifts. It just led to more indecision. User dailydriver on here put expensive Ravenol MT2, a highly regarded MTF, in his T56 after reading all the info posted in one of my prior threads. I was hoping to hear of great results so I could buy it with confidence, unfortunately he updated that he was not impressed with shifting.

So I went with what works. I started compiling old Dex III fluids and used this concoction. 1 quart Havoline MD3, 1 quart Peak Dex III, 1 quart Pennzoil Dex III, and 1 old quart of Mobil 1 ATF.

The old fluid was an ATF of some sort, it was dark red and smelled like honey.

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After the change the transmission shifts like butter! No placebo effect, on my initial drive away it was a little dependent on rpm match to fall into gear and I was disappointed. That quirk stopped after a short time. Tonight I went for a cold start and go, 37 degrees. So smooth, it falls into every gear. Transmission doesn't care what the RPM mismatch is. Downshift to 3rd at 60mph, goes in from idle if you want with no fuss. 6900 rpm WOT shifts in 1rst/2nd/3rd/4th. Not a scratch from a synchro. I'm very pleased.

Total cost to me; $2 for the 1 quart of clearanced Mobil ATF.
 
Cadillac is now mandating your mixture in all their manual transmission cars. Several engineers have quit the company.
 
I am runnning a mixture of Redline and Dex IV in mine. I don't really think a T-56 cares what you put in it as long as it is wet.
 
Originally Posted By: bigt61
Cadillac is now mandating your mixture in all their manual transmission cars. Several engineers have quit the company.


They should quit, the manual states the Dex III factory fill is a lifetime fluid. Surely they jest.

Originally Posted By: ls1mike
I am runnning a mixture of Redline and Dex IV in mine. I don't really think a T-56 cares what you put in it as long as it is wet.


Dex IV, you mean Dex VI? I've read many places that Dex VI is no longer listed as backwards compatible for Dex III in the T-56. GM did not specify this when the fluid first came out but changed later on. That is my memory of it, not sure of the accuracy. I believe it was because it was such a thin fluid, probably fine with your mix.

I had a bad experience with Pennzoil Synchromesh in a T56. Turned a low mileage trans into a very notchy pain to drive in colder weather.

Originally Posted By: Ducman
So you've under filled it?
So you're ignorant on stock capacity? I hate people who post useless [censored] like this.
 
Originally Posted By: Mr Nice
Pictures of car please, I've always thought these were cool cars.


Some pics for you. Not many in this color, most were black or silver. Definitely not the fastest thing I've owned but it's a great all around car. With the cam swap and other bits it makes about 475 horsepower at the crank, a littler over 400 at the wheels. When I bought the car I didn't want it, a friend of mine was having financial problems and needed to unload it fast. I had just sold my 03 Mustang Cobra and had room so I paid off his loan and took the car well under book value. I've had it four years which is a long time for me. I'd like to upgrade to a newer Vette but I don't want to get rid of the Cadillac.

One of the more interesting elements about the car is the gas mileage is incredible. That is mostly due to a smart custom grind cam and me figuring out how to get a lean cruise in the tune and setting strict Deceleration Fuel Cut Off settings. My best full tank average is 30mpg, beating it around for daily use, 21/22.

[img:center]
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Bumper protection when I need it. This car has towed some weight on occasion.


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Originally Posted By: Gasbuggy
They should quit, the manual states the Dex III factory fill is a lifetime fluid. Surely they jest.


Why do people have a problem reading a GM owners manual in regards to transmission service with DEX III fluids?
 
Originally Posted By: Gasbuggy
Originally Posted By: bigt61
Cadillac is now mandating your mixture in all their manual transmission cars. Several engineers have quit the company.


They should quit, the manual states the Dex III factory fill is a lifetime fluid. Surely they jest.

Originally Posted By: ls1mike
I am runnning a mixture of Redline and Dex IV in mine. I don't really think a T-56 cares what you put in it as long as it is wet.


Dex IV, you mean Dex VI? I've read many places that Dex VI is no longer listed as backwards compatible for Dex III in the T-56. GM did not specify this when the fluid first came out but changed later on. That is my memory of it, not sure of the accuracy. I believe it was because it was such a thin fluid, probably fine with your mix.

I had a bad experience with Pennzoil Synchromesh in a T56. Turned a low mileage trans into a very notchy pain to drive in colder weather.

Originally Posted By: Ducman
So you've under filled it?
So you're ignorant on stock capacity? I hate people who post useless [censored] like this.


Talking about ignorance.

GM issued a TSB regarding all T-56 transmissions.
The TSB was in regard to service refill capacity being revised to 4.4 Litres(exactly, and not 4.4 Quarts) with the extra being added into the transmission through the speedometer opening at the rear.
If you put the correct amount in, it will run out of the Tremec factory located filler hole.

From memory the TSB was issued about 2004 or maybe a little earlier.
It pertained to all T-56 Transmissions prior to and after the issue date.
It was strictly a GM initiative.

I think you'll find the TSB will cover your vehicle sufficiently unless it wasn't made by GM.

if you don't believe me, then go and find out for yourself through reputable sources.
The Amsoil website will be a good/quick place to start if you look up your vehicle year and model.
 
Originally Posted By: Ducman

Talking about ignorance.

GM issued a TSB regarding all T-56 transmissions.
The TSB was in regard to service refill capacity being revised to 4.4 Litres(exactly, and not 4.4 Quarts) with the extra being added into the transmission through the speedometer opening at the rear.
If you put the correct amount in, it will run out of the Tremec factory located filler hole.

From memory the TSB was issued about 2004 or maybe a little earlier.
It pertained to all T-56 Transmissions prior to and after the issue date.
It was strictly a GM initiative.

I think you'll find the TSB will cover your vehicle sufficiently unless it wasn't made by GM.

if you don't believe me, then go and find out for yourself through reputable sources.
The Amsoil website will be a good/quick place to start if you look up your vehicle year and model.


Thanks for the complete post this time, I won't need my crystal ball to figure out what you're talking about.

And Ignorance indeed. What your referring to was specific to the GTO/Manaro and it exists because of the angle on the tail shaft for the IRS being greater. My CTS-V along with the SSR truck call for the lowest refill amount of all the T-56 applications; 3.65 quarts. Infact mine was at the weep hole by about 3.8 and when I measured what I took out it was about 3.5.
 
Thankyou for the clarifications on the matter.
I was clearly under the impression that all T-56 transmissions were covered by that TSB from what I had seen here in Australia, and how it pertained to our vehicles produced here.
By the way. It's not a Manaro, it's a Monaro (Smile).

I clearly stand corrected, and bow to your experience.
Please excuse my ignorance regarding your vehicle applications in the US.


Some questions if I may?
Could you further explain why you went with a concoction of Dex III fluids. Some of which are not available here.
In Australia it appears as though Texamatic 1888 is becoming the default fluid for the distributor and Holden dealers, so do you have any experience with it?
What has been your experience to date with any of the thicker fluids available for use in a T-56?
Do you see a useful roll for any of the thicker fluids than the DEX III ATF in a stock standard car fitted with the T-56 that's for all intents and purposes driven normally?
If so, then what do you consider the point at which the use of thicker fluids becomes valid.
 
Originally Posted By: dave1251
Originally Posted By: Gasbuggy
They should quit, the manual states the Dex III factory fill is a lifetime fluid. Surely they jest.


Why do people have a problem reading a GM owners manual in regards to transmission service with DEX III fluids?



They can read it all they want the manual has no service interval for the T-56 in their regular maintenance plan. This is a question/complaint across various forums because it happens with multiple GM performance cars.

There is a special subset for "severe service only" this has you flushing brake fluid and bleeding hydraulic clutch fluid at 25,000 miles. Under severe service they call for 50,000 mile transmission fluid changes, but this is not apart of what they consider regular maintenance for a vehicle. Even though the manual is vague the additional footnote specifies Severe Duty as High Performance Operation, which I assume is referring to cars that see track time. Makes sense considering it was marketed as a 4 door Corvette meant for a road course. But I would disagree with that long interval as well if I was doing High Performance Driving Events. Most would change their drivetrain fluids after just a couples weekends of that driving.
 
Originally Posted By: Gasbuggy
I had a bad experience with Pennzoil Synchromesh in a T56. Turned a low mileage trans into a very notchy pain to drive in colder weather.


The only one I've tried, that actually made the car not driveable, is the RP SynchroMax.
It was not only 'notchy', but EVERY gear ground the blockers/synchros HORRIBLY, and this was in WARM ambient temps!
eek.gif

(Even though some swear by this fluid in their T56es, go figure.
21.gif
)
 
Originally Posted By: Ducman
What has been your experience to date with any of the thicker fluids available for use in a T-56?
Do you see a useful roll for any of the thicker fluids than the DEX III ATF in a stock standard car fitted with the T-56 that's for all intents and purposes driven normally?
If so, then what do you consider the point at which the use of thicker fluids becomes valid.


Given your locale, I cannot see any problems using the thicker MTLs/MTFs (~9.2 to ~10.7 cSt @100*C) out there in a T56/TR6060/TR6070.

I have even used the Red Line MTL (one of the thicker ones) in the SUMMER here, with fine results.
BUT, it WILL cause blocker ring grind on a cool/cold late fall/early winter ambient morning here until it fully warms up.

The Red Line D4 Dex 3 will NOT do this even when freezing cold.
wink.gif
 
Originally Posted By: Ducman
Thankyou for the clarifications on the matter.
I was clearly under the impression that all T-56 transmissions were covered by that TSB from what I had seen here in Australia, and how it pertained to our vehicles produced here.
By the way. It's not a Manaro, it's a Monaro (Smile).

I clearly stand corrected, and bow to your experience.
Please excuse my ignorance regarding your vehicle applications in the US.


Some questions if I may?
Could you further explain why you went with a concoction of Dex III fluids. Some of which are not available here.
In Australia it appears as though Texamatic 1888 is becoming the default fluid for the distributor and Holden dealers, so do you have any experience with it?
What has been your experience to date with any of the thicker fluids available for use in a T-56?
Do you see a useful roll for any of the thicker fluids than the DEX III ATF in a stock standard car fitted with the T-56 that's for all intents and purposes driven normally?
If so, then what do you consider the point at which the use of thicker fluids becomes valid.



Thank you, and my apologies for being abrasive.

I had not heard of Texamatic 1888 before but I looked it up and it is a Dex III fluid. It doesn't meet the new Dexron VI specs, which is a good thing. I would say that is great you have it available to you and your results with it would probably be similar to mine with these old Dex III fluids. I think thicker fluids are fine for warmer climates and people who do extended hard driving. I do not believe that you can find the limits of Dex III on public roads, believe me I have tried and the OEM temp gauge for my T56 has never gotten out of the 170 degree Fahrenheit range. My T56 is original and has almost 190,000 miles on it. It has been supporting more than stock power for quite some time.

The reason I used this concoction, stores in the U.S. don't carry name brand Dex III fluids. There are only cheap store brand mystery Dex III's, like Super Tech from Walmart or Auto Zone house brand. My bottles are probably between 8 to 15 years old. I went digging through my dads rather large collection of mismatched fluids that have made their way to the back of his shelf under a work bench. Old left overs from fluid changes of the past I suppose.

So many options for the T-56, but I had read about too many conflicting experiences with MTFs, Synchromeshes/maxes, full synthetic ATFs (also some well known builders telling customers not to use synthetic ATF because of increased synchro wear). Never really saw people complaining about their factory fill on newer cars or if they changed their own fluid with Dex III.

I could go with a boutique offering but I did not see a reason to pay up to experiment when I had a good option to test at virtually no cost to me.
 
Originally Posted By: dailydriver
Originally Posted By: Ducman
What has been your experience to date with any of the thicker fluids available for use in a T-56?
Do you see a useful roll for any of the thicker fluids than the DEX III ATF in a stock standard car fitted with the T-56 that's for all intents and purposes driven normally?
If so, then what do you consider the point at which the use of thicker fluids becomes valid.


Given your locale, I cannot see any problems using the thicker MTLs/MTFs (~9.2 to ~10.7 cSt @100*C) out there in a T56/TR6060/TR6070.

I have even used the Red Line MTL (one of the thicker ones) in the SUMMER here, with fine results.
BUT, it WILL cause blocker ring grind on a cool/cold late fall/early winter ambient morning here until it fully warms up.

The Red Line D4 Dex 3 will NOT do this even when freezing cold.
wink.gif




I put Pennzoil Synchromesh (9.3 cst?) in my prior 2003 Mustang Cobra T56 around 40,000 miles. Or as I call it now, the Cobro. It was the thing to do at the time, everyone on the forums was boasting about it. "Bro, it shifts sooo much better" Meanwhile I didn't notice that it was posters living in Florida or California falling in love with Synchromesh. I changed it in November/December in Pennsylvania. That transmission shifted just ok on the factory fill. Afterwards I had force it into gear when it was cold, warm it was manageable.

I remember at the time thinking that I wasn't going to lose any races over this so I copied something the Corvette and Z06 guys were doing called "the Anti-Venom Mod" (named that they were always losing to Cobras) where you remove the detent bold and place a thick washer between it to make shifts easier. That was a night and day difference.
 
Originally Posted By: dailydriver
Originally Posted By: Ducman
What has been your experience to date with any of the thicker fluids available for use in a T-56?
Do you see a useful roll for any of the thicker fluids than the DEX III ATF in a stock standard car fitted with the T-56 that's for all intents and purposes driven normally?
If so, then what do you consider the point at which the use of thicker fluids becomes valid.


Given your locale, I cannot see any problems using the thicker MTLs/MTFs (~9.2 to ~10.7 cSt @100*C) out there in a T56/TR6060/TR6070.

I have even used the Red Line MTL (one of the thicker ones) in the SUMMER here, with fine results.
BUT, it WILL cause blocker ring grind on a cool/cold late fall/early winter ambient morning here until it fully warms up.

The Red Line D4 Dex 3 will NOT do this even when freezing cold.
wink.gif



Thanks.
I'm inclined to agree.
My climate here is quite warm most of the time.

Currently running Texamatic 1888 in a T-56 in one vehicle with a slight nibble on the very first selection of first gear when cold in winter.

Also a vehicle with a TKO with the same fluid, and no shift problems at any time.
It's absolutely sublime.
It's quite a high HP application, so I'm looking for some more gear protection even though it breaks traction at the drop of the hat which obviously takes the pressure off the gears at that point.

I'm thinking of changing to Amsoil ATM for the T-56 when due in a few thousand K's.
It's a slight incremental step up in viscosity from the Texamatic 1888.
So I intend to work my way up to thicker fluid in stages and see where the practical limits are.

The TKO is due for it's first fluid change, so I have some Amsoil MTF ready to go in to try in that.

I also have a Billet Pro short shifter ready to go onto the T-56.
I understand it's a good upgrade from the stock unit which improves the 2nd-3rd shift.
Probably because it makes up for poor technique????
Anyway the Shifter will go on first to see what it actually does with the current fluid.
Changing one thing at a time.

I do wonder about the gear wear issue in these things and whether it's such a big issue in reality.
I suspect on the balance of probability the bulk of the problems stem from synchroniser operation, so it's become the main priority for now to improve protection without compromising shift quality.(Obviously)
Only a tear down will reveal the truth of the matter.

Perhaps a tear down of the T-56 will be in order to check gear wear and assess the AW requirements of the Dex III fluid as I'm planning an engine build up in the future for that car.
 
Last edited:
Originally Posted By: Gasbuggy
Originally Posted By: Ducman
Thankyou for the clarifications on the matter.
I was clearly under the impression that all T-56 transmissions were covered by that TSB from what I had seen here in Australia, and how it pertained to our vehicles produced here.
By the way. It's not a Manaro, it's a Monaro (Smile).

I clearly stand corrected, and bow to your experience.
Please excuse my ignorance regarding your vehicle applications in the US.


Some questions if I may?
Could you further explain why you went with a concoction of Dex III fluids. Some of which are not available here.
In Australia it appears as though Texamatic 1888 is becoming the default fluid for the distributor and Holden dealers, so do you have any experience with it?
What has been your experience to date with any of the thicker fluids available for use in a T-56?
Do you see a useful roll for any of the thicker fluids than the DEX III ATF in a stock standard car fitted with the T-56 that's for all intents and purposes driven normally?
If so, then what do you consider the point at which the use of thicker fluids becomes valid.



Thank you, and my apologies for being abrasive.

I had not heard of Texamatic 1888 before but I looked it up and it is a Dex III fluid. It doesn't meet the new Dexron VI specs, which is a good thing. I would say that is great you have it available to you and your results with it would probably be similar to mine with these old Dex III fluids. I think thicker fluids are fine for warmer climates and people who do extended hard driving. I do not believe that you can find the limits of Dex III on public roads, believe me I have tried and the OEM temp gauge for my T56 has never gotten out of the 170 degree Fahrenheit range. My T56 is original and has almost 190,000 miles on it. It has been supporting more than stock power for quite some time.

The reason I used this concoction, stores in the U.S. don't carry name brand Dex III fluids. There are only cheap store brand mystery Dex III's, like Super Tech from Walmart or Auto Zone house brand. My bottles are probably between 8 to 15 years old. I went digging through my dads rather large collection of mismatched fluids that have made their way to the back of his shelf under a work bench. Old left overs from fluid changes of the past I suppose.

So many options for the T-56, but I had read about too many conflicting experiences with MTFs, Synchromeshes/maxes, full synthetic ATFs (also some well known builders telling customers not to use synthetic ATF because of increased synchro wear). Never really saw people complaining about their factory fill on newer cars or if they changed their own fluid with Dex III.

I could go with a boutique offering but I did not see a reason to pay up to experiment when I had a good option to test at virtually no cost to me.



Thanks for the detailed explanation.

Yes there are no 2 experiences the same.
We have to try and find what works for us as individuals.
There has been quite a few people complaining about the shift quality of the factory fill Dex III fluid in the T-56, so they are changing it to something else in order to fix their problems.
Some are having varying degrees of success.
But a Dex III fluid seems to be the fluid that gives the best all round results when the vehicle is driven normally.
Some detailed analysis(patch tests) of Dex III fluid out of T-56's has shown it to be inadequate in terms of protection, with frequent changes required as it's not as good as a dedicated gear lube.

I had considered a boutique oil(Redline D4), but it costs about 2.5 - 3 times the Amsoil offerings.
I think we are well and truly getting gouged here in Australia by the Redline importers.

With regard to your power output on the Cadilac.
I assume you have the LS2 engine from what you reveal in your earlier post.
I would be very interested to know precisely what cam/lifter set up you are running, as the power levels you are getting are right on target for what I'm looking at for my own LS2 build up(approximately 470-480 HP).
Also have you changed the intake, or ported the throttle body?
Are you pulling more revs than stock?
What is your diff gear ratio?
Are you running an M12 variant of the T-56?

I ask because the economy figures you are getting a quite respectable.
 
Last edited:
Ironically, the fluid I REALLY want to try in this gear box is the Penrite Pro Gear 70W-75, which it seems is ONLY available 'down under' in the Antipodes.
frown.gif


Thanks Penrite.
mad.gif
 
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