Non-synchro GL-5 gear oil for a Muncie

[Mark E.]

Re: Non-synchro GL-5 gear oil for a Muncie

Many years ago I decided I was going to go "unconventional" for the lubricant for my 1969's Muncie. I filled it with Red Line 75-90 synthetic gear oil. The result: noticeably smoother shifting, cooler operation, and no leaks.

Maybe gear oil technology has advanced. Every once in awhile, my third gear synchro acts up with a slight crunch while up shifting. I wonder if a synthetic like this might nurse it along better?

[Duke W.]

Re: Non-synchro GL-5 gear oil for a Muncie

This thread prompted me to look at my supply of GM 80W-90 Rear Axle Lubricant I got over 15 years ago.

I just noticed it's a mix of two part numbers, 1052271 and 12345977:
-- The 2271 bottle reads CAS # 64742-65-0 on the back
-- The 5977 label says GL-5 on the front and CAS # 64742-65-0, CAS 72623-83-7 on the back.

Also, the 5977 is noticeably darker in color (see photos. Sorry- no obvious way to rotate them once uploaded; they are right side up on my PC).

When purchased from the dealer back in the day, each were sold as the proper fill for my 1970 M20 (and its differential when the supplement is added). The different PNs were probably purchased in different years.

I wonder why neither label lists GL-4?

The ...2271 product probably dates to the sixties or maybe even the fifties and is likely formulated to the then current Mil-L-2105 spec. Back then it was generally just called "gear oil" and was factory fill and service for axles and manual transmissions. The ...4599 product is obviously a later release and was likely formulated to the then current GL-5 spec, which superseded the canceled Mil-L-2105.

Like engine oil, I expect that gear oil is subject to additive dropout. Turn the bottles upside down for a day or two and check to see if there are any deposits on the bottom of the bottle.

Oils and greases have a nominal shelf life of about three years, but it varies with the product and three years is probablay conservative. Nevertheless, if you are planning a trans or axle oil change I recommend buying fresh 80W-90 GL-5 for the job. In addition to being fresh, current gear oils have better base stock oils and maybe better additive packages.

Grease is an emulsion of oils and solids called "soaps". Over time they separate, so, especially if you are doing a long life grease job like wheel bearings buy fresh grease if what you have is more than three years old or you're not sure of the age.

The api.org Web site has pdfs of "quick reference guides" for both engine oils and gear oils. Gear oil specs range from GL-1 to GL-6 though some are obsolete... same for engine oils.

Duke

[Patrick B.]

Re: Non-synchro GL-5 gear oil for a Muncie

I went to the NAPA store website but it showed that they had Sta-lube GL-5 in stock but not GL-4. So I bought a gallon on Amazon! (its amazing what they have) The Valvoline HP probably would have been OK despite the non-synchro label, and the synthetic Valvoline would probably have assured smooth shifts (but all my Muncie's shift smooothly anyway). However, I had a previous experience with a very early synthetic trans lube that made me think twice. At one time I put a M-22 in my LT-1 and used Amsoil synthetic gear lube, the red stuff, in it. It seemed that it would leak around the cluster gear shaft. That M-22 is still on my shelf and I looked at it yesterday. It was sitting in a pool of red stuff.

Maybe it was just a leaky M-22, but I spent a lot of money having the bottom of my 67 body cleaned on a rotisserie any I didn't want to make oil leaks more probable. The final joke on me was when I went to the NAPA store for the third time to return the Valvoline synthetic, I found a gallon of the Sta-lube GL-4 on the shelf, just like the oil I had already ordered on Amazon.

[Mark E.]

Re: Non-synchro GL-5 gear oil for a Muncie

The ...2271 product probably dates to the sixties or maybe even the fifties...

Oils and greases have a nominal shelf life of about three years, but it varies with the product and three years is probably conservative. Nevertheless, if you are planning a trans or axle oil change I recommend buying fresh 80W-90 GL-5 for the job.
Duke

Thanks Duke!

The bad news is you're saying my stock of GM gear oil has passed its prime and I should just recycle it. I have about 10 bottles.

[Mark E.]

Re: Non-synchro GL-5 gear oil for a Muncie

Many years ago I decided I was going to go "unconventional" for the lubricant for my 1969's Muncie. I filled it with Red Line 75-90 synthetic gear oil. The result: noticeably smoother shifting, cooler operation, and no leaks.

Red Line has separate GL-4 75w-90 and GL-5 75w-90 trans gear oil products. See http://www.redlineoil.com/Products.aspx?pcid=7 .

Regardless of brand, which should be used for the Muncie? From this thread, it looks like the Restorer article says GL-4 while Duke suggests GL-5?

[Joe L.]

Re: Non-synchro GL-5 gear oil for a Muncie

This thread prompted me to look at my supply of GM 80W-90 Rear Axle Lubricant I got over 15 years ago.

I just noticed it's a mix of two part numbers, 1052271 and 12345977:
-- The 2271 bottle reads CAS # 64742-65-0 on the back
-- The 5977 label says GL-5 on the front and CAS # 64742-65-0, CAS 72623-83-7 on the back.

Also, the 5977 is noticeably darker in color (see photos. Sorry- no obvious way to rotate them once uploaded; they are right side up on my PC).

When purchased from the dealer back in the day, each were sold as the proper fill for my 1970 M20 (and its differential when the supplement is added). The different PNs were probably purchased in different years.

I wonder why neither label lists GL-4?


[ATTACH=CONFIG]65677[/ATTACH][ATTACH=CONFIG]65678[/ATTACH][ATTACH=CONFIG]65679[/ATTACH]

Mark-------


Currently known as GM #88863089.

[Mark E.]

Re: Non-synchro GL-5 gear oil for a Muncie

Red Line has separate GL-4 75w-90 and GL-5 75w-90 trans gear oil products. See http://www.redlineoil.com/Products.aspx?pcid=7 .

Regardless of brand, which should be used for the Muncie? From this thread, it looks like the Restorer article says GL-4 while Duke suggests GL-5?

(I've always wanted to quote myself. )

The description for Red Line's GL-4 stuff says, "Safe for brass synchros, as it lacks the reactive sulfurs found in most GL-5 oils that cause damage."

Do M20s have brass synchros? And if yes, is it true we should avoid "reactive sulfers found in most GL-5 oils"?

[Joe L.]

Re: Non-synchro GL-5 gear oil for a Muncie

The description for Red Line's GL-4 stuff says, "Safe for brass synchros, as it lacks the reactive sulfurs found in most GL-5 oils that cause damage."

Do M20s have brass synchros? And if yes, is it true we should avoid "reactive sulfers found in most GL-5 oils"?

Mark------


Yes, ALL Muncie 4 speed transmissions use brass synchro rings. However, all T-10's also use brass synchro rings. GM specified GL-5 lubricant for 1975-81 T-10's as well as 1978-E79 "Muncie" 4 speeds (used for most L-48).

[Mark E.]

Re: Non-synchro GL-5 gear oil for a Muncie

So for Muncies what are we saying, GL-4 or GL-5?

FWIW, Red Line's description of the GL-5 product says, "Musclecar applications like Ford Top Loader, Borg-Warner T-10 and Super T-10, and Muncie transmissions".

[Larry M.]

Re: Non-synchro GL-5 gear oil for a Muncie

This thread prompted me to look at my supply of GM 80W-90 Rear Axle Lubricant I got over 15 years ago.

I just noticed it's a mix of two part numbers, 1052271 and 12345977:
-- The 2271 bottle reads CAS # 64742-65-0 on the back
-- The 5977 label says GL-5 on the front and CAS # 64742-65-0, CAS 72623-83-7 on the back.

Also, the 5977 is noticeably darker in color (see photos. Sorry- no obvious way to rotate them once uploaded; they are right side up on my PC).

When purchased from the dealer back in the day, each were sold as the proper fill for my 1970 M20 (and its differential when the supplement is added). The different PNs were probably purchased in different years.

I wonder why neither label lists GL-4?


[ATTACH=CONFIG]65677[/ATTACH][ATTACH=CONFIG]65678[/ATTACH][ATTACH=CONFIG]65679[/ATTACH]

Mark:

For what its worth, the #1052271 lube I have from around year 2000 is labeled 80W-90 GL-4* on the front of the plastic bottle. The #89021671 that replaced it also has 80W-90 GL-4* on the rear of the plastic bottle. The later lube was purchased this year from some old dealer stock.

The GL-4* indicates it is recommended by GM for use in both manual transmissions and rear axles.

Larry

[Duke W.]

Re: Non-synchro GL-5 gear oil for a Muncie

Good luck using GL-4 in your rear axle. Look at post #14.

I don't understand why some of you buy lubricants from GM dealers. What they sell is for MODERN cars. They could care less about your 50 year old Corvette.

For the OP: You now have the recommendations and reason for and against each. Mine are in post #14. If you can't decide, just flip a coin.

Duke

[Mark E.]

Re: Non-synchro GL-5 gear oil for a Muncie

Good luck using GL-4 in your rear axle. Look at post #14.

I don't understand why some of you buy lubricants from GM dealers. What they sell is for MODERN cars. They could care less about your 50 year old Corvette.

For the OP: You now have the recommendations and reason for and against each. Mine are in post #14. If you can't decide, just flip a coin.

Duke

Thanks Duke. I always value your expertise and time.

I bought my GM gear oil from the dealer in the early 90s when my '70 Corvette could still be considered (almost) modern...

[Patrick B.]

Re: Non-synchro GL-5 gear oil for a Muncie

Good luck using GL-4 in your rear axle. Look at post #14.

I don't understand why some of you buy lubricants from GM dealers. What they sell is for MODERN cars. They could care less about your 50 year old Corvette.

For the OP: You now have the recommendations and reason for and against each. Mine are in post #14. If you can't decide, just flip a coin.

Duke

Duke ---- My original question never got answered. The Valvoline HP 75w-90 GL-5 gear oil was labeled for non-synchro transmissions. The Valvoline website recommended other oils for synchronized manual transmissions, but the NAPA people never heard of the other products. The synthetic GL-5 was labeled for all manual transmissions but I was afraid the synthetic was more likely to leak. Buying GL-4 was a responce to my continued ignorance. Why would a GL-5 oil be recommended by Valvoline only for non-synchro transmissions and diffs?

[Joe L.]

Re: Non-synchro GL-5 gear oil for a Muncie

Duke ---- My original question never got answered. The Valvoline HP 75w-90 GL-5 gear oil was labeled for non-synchro transmissions. The Valvoline website recommended other oils for synchronized manual transmissions, but the NAPA people never heard of the other products. The synthetic GL-5 was labeled for all manual transmissions but I was afraid the synthetic was more likely to leak. Buying GL-4 was a responce to my continued ignorance. Why would a GL-5 oil be recommended by Valvoline only for non-synchro transmissions and diffs?

Patrick-------


As I mentioned above, GM specified GL-5 lubricant for 1975-81 Borg Warner T-10's as well as the 1978-E79 "Muncie" 4 speeds used in Corvettes and other GM cars. The T-10's and 78-E79 Muncies are fundamentally no different than 1963-74 Muncie transmissions. So, I have no idea why Valvoline would not recommend GL-5 for synchro type transmissions; GL-5 is what GM says to use.

[Joe L.]

Re: Non-synchro GL-5 gear oil for a Muncie

Good luck using GL-4 in your rear axle. Look at post #14.

I don't understand why some of you buy lubricants from GM dealers. What they sell is for MODERN cars. They could care less about your 50 year old Corvette.

For the OP: You now have the recommendations and reason for and against each. Mine are in post #14. If you can't decide, just flip a coin.

Duke

Duke------


I cannot find that GM ever offered a GM-branded lubricant for most manual transmissions. They did offer specialty lubricants for very specialized and narrow-application manual transmissions but all of these are long-since discontinued.

You will note that GM #1052271 and supercessive part-numbered lubricants are identified as "Rear Axle Lubricant". Rear axle applications are the ONLY applications that GM specified these lubricants for use. It's possible that these lubricants could be used for manual transmissions but GM never said that. GM did specifically instruct that the GM #1052271 be used for limited slip rear axles.

I cannot find that GM ever specified a specific GM part-numbered lubricant for any 1957-81 Corvette manual transmission. For 1957 to about 1974, they simply specified an SAE 80W or SAE-80W-90 "Multi-Purpose" gear lubricant meeting U.S. Army Ordinance Specification MIL-L-2105B. From about 1975 to 1981 they specified the use of SAE 80W or 80W-90 GL-5 lubricant.