Front axle oil GL-4??

[loggin]

Came across this Kubota lubricant chart from another thread here on TBN and was looking at the GL-4 requirement of the front axle 80w90 gear oil alternative to the UDT. As I recall the 80w90 I used was a GL-5. As I did a search I am finding it hard to locate GL-4 80w90 at my local stores. From what I understand the GL-4 uses half the amount of additives compared to GL-5. Sulfur/Phosphorus additives are part of the make-up and can be corrosive to certain metals.

Wondering why Kubota requires GL-4 as opposed to GL-5 in their front axles??

Kubota | Lubricant & Grease Maintenance Schedule

Browse our Oil and Grease Maintenance guide for equipment lubrication involving grease and oil for Kubota's products. Learn more with Kubota service support.

www.kubotausa.com

 

[big bubba]

don't quote me until someone more informed than me replies. my guess is that your manual is outdated & that GL5 will be just fine. i gather that the current additives may have been corrosive to the antiquated brass (or other) bushings in the past, etc. but your model is modern & is suited for current gear oils.... i have always used GL5 with no issues. just call your dealer service dept to confirm, best regards

 

[tomplum]

GL5 isn't always backwards compatible for the reasons you listed. You can still find GL4 easy enough and you really don't have the need for the extra additives anyways.

 

[JWR]

To heck with it. Use whatever 80W90 jug is handy and don't fret. It will outlast you regardless of GL4 versus GL5 , etc.

 

[arto98607]

As far as I recall GL4 is recommended by manufacturers when there are some brass parts involved....corrosion I think.

Should not be hard to find it - I bought from O'Reilly Auto Parts the last time I needed some.

 

[loggin]

From what I also understand GL-4 is used when soft metals, like brass, are used in a manual transmission or transaxle with synchromesh. Therefore I do not understand why Kubota would recommend GL-4. I do not believe there are soft metals in the front axle or am I mistaken..??

 

[Fixastuff]

Royal purple has the only gl4 I can find locally. Redline also had a gl4 but I can't find it anymore. If you ever compare gl4 to gl5 the 5 is much stinkier lol.

 

[number two]

Kubota manuals are woefully out of date on fluid specs.
Been that away as long as I can remember.
Maybe someone that speaks/reads Japanese could get a position editing Kubota literature.
Forget that-nobody works anymore!