Oil confusion

[dirtyfingernails]

Sorry to beat a dead horse, but I'm a little confused and not a chemist. The LO indicates that GO should go into the transmission, t-case, and diffs (80/90 weight). There is no mention of GL-1 etc that I could find, only specifications at the back of the manual. Specifically, MIL-L-2105. I recently put 80/90 gear oil in my rear diff, but it only states that it meets GL-5 specfications. I don't want to damage what I have, so could someone just tell me what I should use? I have a NAPA nearby and Tractor Supply. Thanks much!
Steve

 

[devilman96]

GL5 replaces GL1 and exceeds its specs.

 

[acetomatoco]

GL1 is more than adequate for your truck which was designed in 1949...and is a lot less expensive than GL5. The choice is yours. Just like the engine which will tolerate Diesel rated oil of 10W or 30 by season, or use the 15-40 year round ...again your choice... Here in Northern Vermont at 30 below zero..they sure start easier with 10w ...

 

[CGarbee]

In another post (reply to one from Cranetruck) that I made a while back (I'll dig around and will see if I can find it), I posted the relationship between the Milspec and the API ratings for OE and GO...

To be perfectly safe, you want your GL5 to also have the MT1 rating in order to ensure that you will not harm yellow metal components in your driveline. Most GL5 meets the MT1 requirements, some do not. If you don't see the MT1 rating, look at the fine print on your lube container and you should see a list of MACK, Volvo, MIL, ect specifications. If it has the current Mil number, you should be good to go.

For that matter, we've also mentioned the 50wt is what Spicer really specifies for the transmission...

As Ace says, GL1 works just fine and is a lot less expensive and is what the military has been pumping into these things for years... I also use it and have had zero problems...

 

[dirtyfingernails]

GL-1 all round. Thank you.

 

[comdiver]

I was just making a list of the lubricants that I needed. In checking LO 9-2320-386-12, 15w40 is listed not only for the engine but for the transmission as well.Any feedback?

 

[emmado22]

What about the 15W-40 for the tranny on the M35A3's? Uncle Sam has been trying to reduce the amount fo different types of oils that need to be carried at the unit level..... The FMTV's use the same oil for the engine and tranny also...