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Just picked up a "new" M38 and decided to change all of the fluids in order to create an accurate timeline for maintenance. I drained the transfer case oil with no problem. The problem was finding the proper oil refill the transfer case. I did a little research and it looks like GL-5 gear oil with the anti-slip additives is corrosive to the components in the transfer case/transmission. I found a gear oil that was rated "GL-4/GL-5", but wasn't ready to take the chance. I decided to go with a 30W Non-Detergent which matched up well with the gear oil on the viscosity charts. After a short test drive and two nights in the garage, I have a drip pan full of fresh oil which is pretty irritating. I assume this is due to the thinner oil.

Does anybody have any ideas/guidance on the issue. What fluids do you use in your transfer case/transmission/axle/motor? What have you seen work well with those components?

I'm going to use GL-1 gear oil I found at napa. I believe it is 80-90 wt. mineral oil. It was also at a very decent price. I will use regular GL 4-5 gear oil in the two axles.

Hi,

I thought this document was already on the site, but I couldn't find it!

http://www.bill-capes.com/Insanity/imag ... _Sheet.pdf

shows that you should have used 90 weight on both transfer case AND transmission.

Help yourself to a copy!

Bill

capescw wrote:Hi,



http://www.bill-capes.com/Insanity/imag ... _Sheet.pdf


Help yourself to a copy!

Nice chart Bill!! Sent it to my color photo printer for a nice 8.5 x 11
color photo suitable for framing and to hang above the workbench..

Thanks fellas!

I use Ford Tractor Transmission fluid from Tractor Supply Company, Traveller Brand. It is GL1 and fairly cheep.

http://www.tractorsupply.com/en/store/t ... _vc=-10005

I use the 90 wt GL-1 from NAPA. They have gallon jugs available.


Hello from Offutt AFB!

Looks like I'll be going to NAPA tomorrow. Good to see another airman with an m-series. RC aircrew I presume?

Foxmike Have you had good luck with the napa GL-1 oil? I don't have my jeep running yet so I can't report on it yet.

You can look up maintenance procedures and recommended lube types in TM9-8012, M38 Maintenance, in the Downloads section of this website. It has the military version of the lube chart already mentioned above. There are a bunch of previous threads on lubrication. Here is one that may be of interest: http://www.willysmjeeps.com/v2/modules. ... hlight=gl4
GL1 oil is for light duty operations but GL4 can be hard to find in some locations. You can order it on-line. I decided to use 50 wt. racing motor oil for my last trans fill, working well so far. You can use GL5 for the axle pumpkins.
Your drip pan full of oil is a common issue with these jeeps, not really caused by thinner oil, its caused by leaky/worn seals. I just replaced the seals in my trans/transfer for that reason.
Good luck with your new Jeep!

Skyjeep Thank for posting all of that good information. I certainly learned a few things.

HBarn752 wrote:Looks like I'll be going to NAPA tomorrow. Good to see another airman with an m-series. RC aircrew I presume?

Yep. Everyone loves the jeep on base.

Billybob- I'm by no means an expert mechanic, but the GL1 has been working fine for me. Picked that based on reading this and other forums. I just do light driving so didn't see the need for heavy duty gear oil.

Thanks Foxmike - It sounds like we both have about the same driving habits. I think My old jeep has done it's share of hard work and now it's time for a little easier life.