FLYER15015

GL-4 or GL-5 for your Tx

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In the process of waking up the "Baby", we pulled her out of the car hauler, where she's been sleeping, and put her in the garage to start working on her.

Lucky we did this yesterday, as it is now snowing. 4" so far with more to come.

 

Anyway, I was doing some research on the various "fluids" required, and I came across an article from "bobtheoilguy.com" which stated that for the Tx in a 3 speed gearbox with bronze syncro rings, you MUST ONLY use GL-4 gear oil, as the more common GL-5 has a set of additives that are not kind to yellow metal parts.

GL-5 or GL-4/5/6 is fine for our old differentials, but not for the gear box.

G.M. has a part number listed for their manual Tx's which is 12345349, and several oil companies such as Penzoil and Valvoline make the stuff. I'm sure others do also in both dino oil and synthetic blends,

 

I did a search on our forums and could not find a thread that addresses this issue, though several Corvette and Corvair forums seem to validate "bob's" thinking.

 

I just wanted to put this out there and see what you folks think.

 

Best Regards,

Mike in snowy Colorado

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Redline makes GL-4 manual transmission lubricants.   I love this stuff and I use it in all my manual transmissions from a 1984 BMW to the 1922 Dodge.  I use MT-90, but there are several other viscosities.  Great stuff that improves shifting and is kind to the internals.  Amazon delivers it to the door too.  I used 600W in the Dodge transmission once.  The original recommended lubricant.  Shifting was terrible.  Lots of grinding to go into gear.  Too much molasses.  This stuff is far superior.   Hugh

 

http://www.amazon.com/gp/product/B000CPCBEQ/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

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Last Sunday I changed both the transmission and differential oils on my '41 Limited. After asking here and looking around the corners of the Internet, it appears that some kind of 90-weight GL-4 is the right choice. I learned a lot about oils while doing my research, and what I ended up using was 85W90 GL-4 non-synthetic gear oil called STA-LUBE, which is sold by NAPA (http://www.napaonline.com/napa/en/p/SLRSL24239). They didn't even know they stocked it when I went in the store, but when they looked on the shelf--voila!--there it was. I used it in both the transmission and the rear end. It was about $38/gallon and a gallon was just about enough for both the rear end and the transmission on the Limited, which uses a larger pumpkin than the smaller series cars.

 

It's worth noting that despite their naming convention, the gear oils are not multi-viscosity like motor oils. They do not have polymers or modifiers in them. Instead, there's a fairly wide window for what you're allowed to call "90 weight" and the closer the first number is to 90, the thicker the oil (i.e. the closer it is to actual 90 weight). There's 75W90 and 85W90, and I chose the 85W90, which is the thicker of the two. Since the manual calls for 90-weight, that should be pretty close and the quality of a GL-4 oil should be superior to what they were using in 1941. Don't let anyone tell you that GL-5 is OK, because while it's technically reverse-compatible, it has modifiers in it that will hurt your synchros. Probably won't hurt the differential any, but when the right stuff is available, it seems like a no-brainer to use it.

 

The result is that the car feels almost exactly the same as it did before. I replaced the shifter bushings and adjusted the linkage while I was under there, and it does shift very well now, but I can't say whether that's the result of the oil or the bushings. It's smooth with no clashing and the gears are quiet (not silent, as I'm sure you know--these Buicks have a nice gear whine as they accelerate). I'm just happy to have fresh oil in there--who knows how old the other stuff was?

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I use GL1 140 CLASSIC GREEN GEAR OIL in the summer for the 38 Special transmission. I change it to GL1 90 CLASSIC GREEN GEAR OIL in the winter. The label states "free of EP additives for vintage applications".  I don't use this in the rear axle, only the transmission. It is made by MILLER OILS and I buy it and get it delivered from AMAZON.COM. I use STA LUBE GEAR OIL 85 90 GL4 HYPOID in the rear axle.

 

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I believe that GL1 is also available at places like Tractor Supply. It is the gear lube used for older tractors like a Ford 8N, etc.

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I do know that the spider gear Thrust bushings are brass on my 32 Buick differential.  I use the GL4 in there also.  Why risk it, and it's easier to have just one lubricant when practical.

 

Bob Engle

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On ‎4‎/‎28‎/‎2016 at 2:42 PM, LAS VEGAS DAVE said:

I use GL1 140 CLASSIC GREEN GEAR OIL in the summer for the 38 Special transmission. I change it to GL1 90 CLASSIC GREEN GEAR OIL in the winter. The label states "free of EP additives for vintage applications".  I don't use this in the rear axle, only the transmission. It is made by MILLER OILS and I buy it and get it delivered from AMAZON.COM. I use STA LUBE GEAR OIL 85 90 GL4 HYPOID in the rear axle.

 

That's cool Dave.

You drive a '38 Buick with no emission controls what so ever, and you use "Green Gear Oil".

Like Larry the cable guy says, " I don't care who you are, THAT"S FUNNY !"

 

Just kidding Dave, DRIVE ON !!!!!!!

 

Mike in snowy Colorado. 8" and still coming down.

Edited by FLYER15015 (see edit history)

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3 hours ago, LAS VEGAS DAVE said:

Mike, mine is a 38 Buick not a 37 but they look very similar. 

OOOOPS,

Went back and fixed my post.

Sorry,

Mike

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Mike, here is a doc that may help. It was written by a Corvair person (gasp!) for it lays out the differences pretty well. Maybe this is what you were referring to ear;ier, but I thought maybe others would want to read it.

 

Cheers, Dave

 

Transaxle_oil.pdf

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8 minutes ago, Daves1940Buick56S said:

Mike, here is a doc that may help. It was written by a Corvair person (gasp!) for it lays out the differences pretty well. Maybe this is what you were referring to ear;ier, but I thought maybe others would want to read it.

 

Cheers, Dave

 

Transaxle_oil.pdf

 

That's a great document--I gleaned a ton of information from it, summarized in my post above. Dave also confirmed my choice of lubricant as the right one for these cars. Thanks, Dave!

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Hi Dave,

Yup, that is one of the papers that I referred to in my initial post.

Thanks for posting the link .

 

Mike in snowy Colorado. Got 8"today and more on the way.

 

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