Is GM Synchromesh really no good? I can't find the post, but I read on here that that was one of the acceptable oils, along with Syntorque and the proper Dodge and Chrysler stuff. It does say it's for manual transmissions, not differentials, on the label.

If it's gonna harm my tranny i better drain it quick since I've got 2500 miles on it already.

 

You could be right, maybe all GM gear oil is called Synchomesh.
I only know it as differential lube.
Never used the GM tranny oil and have only seen it described as GM Transmission Oil (PN 12346191) not Synchomesh.

 

http://www.pzlqs.com/Tech/Pdsheet/Do...omeshFluid.PDF
hope the link posts right. dont see the proper part# listed there. is there a conversion we should be doing or is this stuff just not the right stuff? just want to know because its whats in my tranny right now and i didnt put it there.

 

The link you gave pretty much says it won't work:
PENNZOIL® SYNCHROMESH FLUID is NOT intended for all GLS applications. You
must verify the manufacturer’s part number, indicated by a superscript number and found at the end of the vehicle
application listing.

GM p/n 12346191 isn't on the list.
Personally I wouldn't trust it and would dump it.
These trannies are just too expensive to repair.

 

what is GLS? and what is a superscript number? i personally would have never put this stuff in my tranny if there was any doubt. the problem is that i had someone do it and i want to nail him for fresh proper oil.
thanks.

 

GLS = Gear Lube - Special
These are lubricants speced by the manufacturer for certain transmissions almost always to ensure they are not damaged by using lubes with chemical properties that can do harm to the construction materials.

An example would be using a lube with sulphur compounds in a tranny with yellow metals (bronze, copper, etc.)
The chemical reaction between the two can be disastrous.