Transmission Gear Oil GL-4, GL-5

Mon May 06, 2013 6:17 pm

I need to change the transmission oil in my 1956 Cub. I read here that the Cub transmission requires a GL-4 gear oil and that a GL-5 may do harm. When I looked for gear oil today I found that it is now typical for gear oils to be labeled both GL-4 and a GL-5. Are these multi-rated gear oils safe for the older Cub transmissions? I would use Hy-Tran but I am concerned about gear noise and the increased possibility of leaks.

Re: Transmission Gear Oil GL-4, GL-5

Mon May 06, 2013 6:20 pm

In my experience the level of gear noise is the same whether you use gear oil or hytran. I just switched the gear oil in my SC to hytran and could tell no difference in the noise level

Re: Transmission Gear Oil GL-4, GL-5

Mon May 06, 2013 7:26 pm

There are no bronze parts or synchros in a Cub transmission. Use whatever you want- it is a low speed gearbox. Water is the enemy. Hytran keeps it in suspension.

Re: Transmission Gear Oil GL-4, GL-5

Mon May 06, 2013 8:15 pm

bob in CT wrote:There are no bronze parts or synchros in a Cub transmission.


What about the PTO pilot shaft bushing and the reverse idler gear bushing? Definitly not a synchro, but definitly bronze.

Re: Transmission Gear Oil GL-4, GL-5

Mon May 06, 2013 8:23 pm

You are right. There are a couple of bushings. :)):

Re: Transmission Gear Oil GL-4, GL-5

Mon May 06, 2013 8:52 pm

Use Hy Tran and you will have nothing to worry about, if the seals leak then they needed to be replaced anyway!
Boss

Re: Transmission Gear Oil GL-4, GL-5

Tue May 07, 2013 7:48 am

Valvoline has GL-4 and TSC has mineral oil :D

Re: Transmission Gear Oil GL-4, GL-5

Tue May 07, 2013 10:00 am

GL-1, 140 wt, is still available at local farm and ranch supply store.

Re: Transmission Gear Oil GL-4, GL-5

Sat May 11, 2013 11:28 pm

I found quarts of 80-85W GL-4 at Napa. I drained at least a gallon of oil from the transmission. It was clearer and thinner than I would have expected. I then flushed it with 3.5 pints of kerosene before filling it with the correct amount of gear oil. I am guessing it had Hytran it it and that the Hytran had absorbed at least it's own volume in water.

Re: Transmission Gear Oil GL-4, GL-5

Sun May 12, 2013 12:05 am

Xperimental wrote:I am guessing it had Hytran it it and that the Hytran had absorbed at least it's own volume in water.


Apparently that is what Hy-Tran is supposed to do .. absorb the water. With gear oil, the oil will turn milky as the water contaminates it. If there is water in the tranny, then it means the gasket isn't doing it's job or the shield has worn allowing water into the tranny. No matter what fluid is used, the problem of moisture/water has to be addressed I would think.

Re: Transmission Gear Oil GL-4, GL-5

Sun May 12, 2013 5:54 am

Bought the 53 and last fall changed all fluids. including transmission and pto...Tractor has been in the barn all winter....Have to do some work on the pto, and the transmission etc had water in it...(from power washing maybe)....Anyhow that was with 90 weight...Will be switching to Hy-Tran...Dave