gonefishn

There have been many threads on transmission fluid before but just wanted to share one more for reference.

Was buying something else when I saw on the shelf three bottles side-by-side of 85W90W fluid with the first labeled GL-4, the second GL-5, and the third GL5+.

Reading the backs, only the GL-4 said protects copper, brass and non-ferrous metals used in synchros.

Bought a bottle and am now torn on replacing the fluid or not. First time I ever came across an only GL-4 rating. The GL-5 stated it met the MIL-L2105 too but did not claim to protect certain metals.

mikem350

Use the GL4, as has been hashed around before (search the archives). My local Advance Auto even has manual trans fluid, rated GL4! GM dealers sell Syncromesh fluid also.

GL5 is for rears and has additives that some think will attack the brass syncros (with heat and time)

BADBIRDCAGE

Anybody selling Pennzoil should be able to get you the Synchromesh fluid. We have it at the NAPA I work at.

Rich

Plasticman

What was the brand?

Plasticman

Sky65

I could not find GL4 around here in quarts. I ended up getting Pennzoil
GL4 from the local Jiffy Lub. They have it in bulk. I had the guy pump a few quarts into a clean plastic jug.

gonefishn

The brand is labeled "Sta-Lube".

Plasticman

Thanks. Have seen that brand at Pep-Boys in the past.

Plasticman

gonefishn

Would you also recommend using the GL4 instead of GL5? Noticed the GL5+ didn't meet the MIL standard.

Plasticman

I have a MY6 trans (GM 4 speed OD) in my Vette. Back when we first installed it, wmf62 had done a search on which lube we should use (he installed one as well). At that time Valvoline stated that their standard mineral oil based GL5 (80W90) would not harm the brass synchros.

http://www.valvoline.com/pages/produ...sp?product=114

However, I see that on their website, they do not list the additive package for that product, but do for their Synthetic Gear Lube. That spec shows that it contain sulfur (which as I understand it, is the main additive that eats brass). So I am wondering if the info that Bill received was correct.

http://www.valvoline.com/products/Sy...ear%20Oils.pdf

The Valvoline has worked fine for 2 years, but for the long term I am concerned that the GL5 will damage the brass. I will need to "explore" the GL4 further.

Note that we were told that the Mopar version of the MY6 (the A-833) can use ATF, but these old trans are "loose" and leak a drop or 2 with the heavy gear oil. The ATF would probably need a refill once a month!
Never did find out what lube GM recommended for them.

Thanks,
John

wmf62

the info i received from Valvoline about the compatibility of their GL5 lube was by email (don't have that email anymore, but i contacted just about every lube manufacturer) directly from Valvoline; not sure what else i can say...

as i remember asking the local GM dealer, GM used ATF....
Bill

wmf62

i received the following email from Valvoline..

Valvoline products meet both GL-4 and GL-5 specifications, meaning that our gear oil products are completely safe for yellow metals, (brass, copper, etc.).



To: VWEBMAIL@Ashland
cc:

Subject: Site feedback from Valvoline.com


The following person submitted a question or comment via the Contact us form of type Other Product
First Name: Bill
Last Name: Fleckenstein


Comments:

i understand some formulations of transmission lube can damage brass parts, such as synchro rings. can your GL5 lube be used without affecting the brass parts?

Bill

Plasticman

Bill,

As per my e-mail back to you, I still am not satisfied with an e-mail that "says" it is OK. If they use sulfur in the Synthetic version, they probably use it in the mineral version. If so, how do they account for that?

Their packaging does not say it meets GL4 specs, nor does their website.

It would be nice to have something more than just an e-mail, and they should be proud to print it on the packaging if it is so.

Thanks for checking into it.

Plasticman

Nev Williams

John,
I've just gone thru all this Gear Oil Additive Spec stuff when installing a new AGE Supercase Muncie. A sheet came with the Gearbox from them
quote

"Assemblies are shipped without oil. We recommend filling your new transmission with a good quality SAE90 gear lubricant meeting API specifications 'GL-4' or 'GL-5 AND MT1'. DO NOT use GL-5 lubricants without the MT-1 label; the EP additives in unmodified GL-5 lubricants have been found do damage the bronze used in bushings and synchronizer rings."

I rang them up and had an informative chat as to make/type/grade of oil. From that conversation I ended up putting using Pennzoil 80W/90 EP it has both these specs. From what I learnt, the MT1 spec was created for just this problem with bronze parts in gearboxes. I believe it was also an issue in large truck manual gearboxes. I figure the MT stands for Manual Transmission

Plasticman

Nev,

Thanks for the info!

Here is another thread (diff. forum) that is along the same lines, but stated that the additive that causes the problem for yellow metals, only becomes corrosive above 250 F degrees. I guess I don't have to worry as much as I do!

Here is the blurb:
""A GL-4 or, to a greater extent GL-5, lubricants can, if not properly

formulated, become corrosive to yellow metals if the lubricant temperature

exceeds 250 degrees F. The API recently came out with a new specification to

address this possibility. It's called MT-1. You'll find that AMSOIL gear

lubes all meet this new spec. therefore do not attack yellow metals. Two

things work in your favor if AMSOIL Synthetic gear lube is used. 1. AMSOIL

will run cooler, reducing the possible high temperature situation. 2. AMSOIL

gear lubes meet MT-1, therefore will not attack yellow metal even if the

temperature does climb to this extremely high 250 degree mark.""

And yes, the Valvoline Gear Oil that we have been using is rated MT-1.

Plasticman

DZAUTO

I have a 5gal pump dispenser (got it from an old gas station that closed) and buy GL4 in gallon jugs from NAPA.

GCD1962

Yes, you want the MT-1 designation. Be sure to check the label as even some brands such as Valvoline, Pennzoil and others sell GL-5 both with and without the MT-1 properties.

C66 Racing

Most AMSOIL gear lubes meet both the GL-5 and MT-1 specifications. Probably the best is the diff fluid that I use in my C5 Z06 track use only diff and the diff in my 06 CTS-V diff - a good fluid:
AMSOIL Severe Gear Extreme Pressure Synthetic 75w90

C2Bill

I put in Redline MTL (70w80), works great. Shifts much better, it is a GL4.
C2Bill

GCD1962

This is the correct answer

wmf62

FWIW, to add to my previous input...

i gave up using any 'normal' gear lube in my MY6, i was getting synchro clash when downshifting; i changed to ATF, as originally used by Mopar & GM, and have never had another problem.
Bill