05 GMC 2500 4L80E Fluid options

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Okay so i have a 2005 GMC 2500 gasoline destroyer that has 190k on it now. Original trans is leaking and i happen to have a matching GM 4L80E Goodwrench trans new in the crate. Trans on the truck is fine other than the miles and leak. I've got a shop that will swap it for a good price. I can sell the still working 4L80E to someone looking to build a trans.

So, if you had a fresh 4L80E what fluid would you use? Dex VI? Something in the Dex III viscosity range? I'm tempted to spend the cash for Delvac 1 ATF. I don't tow heavy and this rig sees about 5k miles a year or less. Seems GM has back dated Dex VI for these units but some people say it doesn't work well while others praise it.
 
dexron VI will work just fine. Been running it, AMSOIL's version ATL in my 2002 Silverado's 4L60E now for 50k miles with 175k on the transmission with no issues.
 
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Maxlife ATF is good stuff. Plus, it may help with the leak, too.

If your transmission doesn't have a drain plug, get the Dorman pan
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4L80E's are not picky about fluid because the "straight through" nature of the unit.....One clutch applies right after the other for ratio changes unlike other designs that have to release one clutch at the same time another clutch comes on to change ratios.

I run Castrol Transynd in all my GM transmissions with great results, It's basically the same as TES-295 Mobil Delvac 1 but a little cheaper. I buy it at Inland Truck Parts for @ $38 a gallon.

Dexron VI will also work great.

I wouldn't be so quick to install a "Goodwrench" unit over a leak & mileage alone, I have tore apart hundreds of the Goodwrench Service Replacement Transmission Assembly (SRTA) units.....Not impressed! Most are 10 different units thrown together to make one working unit. It's so bad I WILL NOT buy cores with SRTA stickers on them.
 
Amsoil Torque Drive ATF is the thicker formula for HD transmissions. Similar to Castrol Transynd in application specs.
I would personally run Torque Drive or Amsoil Signature Series Multi vehicle atf.
 
When you say STRA is that a grade of GM reman transmissions or are they all questionable? The one i have looks like a perfect brand new unit and doesnt say STRA.
 
What's leaking specifically? Pan gasket?

Maybe just change the gasket and sell the crate transmission? It could probably bring a pretty penny.
 
Originally Posted By: Nick1994
What's leaking specifically? Pan gasket?

Maybe just change the gasket and sell the crate transmission? It could probably bring a pretty penny.


I haven't gone under to check the source of the fluid but it will slowly drip even when its not running. I suspect the pan gasket. I acquired two of these crate transmissions and it took a while to sell one. Most buyers just wanted a core they could build up, so i figure i might as well go to a fresh unit for my truck and sell a nice core to somebody for not much less money.

It needs a drive shaft bearing done too and i'm just too lazy to really work on it since its too big for my garage space and my driveway is sloped.
The truck also makes some wierd high pitch whine noise when its really cold outside, goes away in a minute or two.
 
Originally Posted By: dareo
When you say STRA is that a grade of GM reman transmissions or are they all questionable? The one i have looks like a perfect brand new unit and doesnt say STRA.


To my knowledge ALL Goodwrench automatic transmissions are remanufactured and all are the same grade, GM Performance Parts is selling NEW 4L85E's using leftover new parts from the Willow Run plant where all 4L80E were manufactured 'til it's closure in 2010 & the end of 4L80E production.

This is what a STRA rebuild tag looks like.
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Update: I finally got around to taking my truck and new 4L80E in to get installed. I used Fleetrite TES-295 spec fluid. Before it had the original 191k mile trans running on some maxlife ATF.

The result? Butter smooth shifts. I imagine this is what the truck was like to drive when it was new. My old trans doesn't have anything wrong with it other than wear. This new unit is quite the difference. Long story short, i put a brand new trans in a truck that didn't even 'need' it and couldn't be happier.
 
Sounds like it was the right move. Hopefully you will get a long service life out of this new one.

I have a 98 chevy K3500 with this transmission in it and am currently running Supertech high mileage tranny fluid in it. I probably need to run something else in it because sometimes during the winter when it's really cold and the truck hasn't been driven in awhile, it take it a few seconds to go into gear. The truck only has 116,000 miles on it but I don't know how it was used before I got it when it had 94,000 miles on it.
 
Originally Posted By: wtd
Sounds like it was the right move. Hopefully you will get a long service life out of this new one.

I have a 98 chevy K3500 with this transmission in it and am currently running Supertech high mileage tranny fluid in it. I probably need to run something else in it because sometimes during the winter when it's really cold and the truck hasn't been driven in awhile, it take it a few seconds to go into gear. The truck only has 116,000 miles on it but I don't know how it was used before I got it when it had 94,000 miles on it.


The converter drains back through the Stator Bushings, Even a with new bushings the converter will drain back if given enough time.

It's when it does it overnight that you need to be concerned.

A good synthetic fluid will probably fill the Converter faster at low temps.
 
Originally Posted By: clinebarger
Originally Posted By: wtd
Sounds like it was the right move. Hopefully you will get a long service life out of this new one.

I have a 98 chevy K3500 with this transmission in it and am currently running Supertech high mileage tranny fluid in it. I probably need to run something else in it because sometimes during the winter when it's really cold and the truck hasn't been driven in awhile, it take it a few seconds to go into gear. The truck only has 116,000 miles on it but I don't know how it was used before I got it when it had 94,000 miles on it.


The converter drains back through the Stator Bushings, Even a with new bushings the converter will drain back if given enough time.

It's when it does it overnight that you need to be concerned.

A good synthetic fluid will probably fill the Converter faster at low temps.



Is synthetic recommended for these older transmissions? The reason I ask is that years ago, I used Mobil 1 synthetic tranny fluid in my 98 chevy K1500 with the 4L60E and it didn't seem to like it. The trans seemed like it was slipping. I changed back to a conventional fluid and the tranny seemed to operate normally again. I bought this truck new and it didn't have high mileage on it when I used the Mobil.
 
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