I just changed the transfer case fluid on my MTVR yesterday, i went and used straight weight detergent SAE 40 oil in mine. I figured the military had lots of 15w40 oil around, lord knows they use it in almost everything else on the truck... if they specced something different for the TC, there was good reason.
I was able to find that oil at local parts stores, surprised me a bit, never noticed it before. Ive used straight 30 weight a number of times for various things over the years (both detergent and non detergent depending on application). I did have to go to 2 parts stores to get full amount tho, no one place had enough.
FYI, i bought 7 quarts, which was good bc mine took about 6.3 quarts, and truck was level (actually was jacked up a few inches in front, bc changing front hub oil so needed it lifted up slightly to be able to rotate wheels to correct position). That would tilt TC up slightly, make fluid run out of fill hole slightly easier.
So, long story shorter, mine took a bit more than 6 quarts, but if you put 6 quarts in i suspect youd never notice difference. Same w using 15w40 oil....
One last thing, the TC fluid was kind of milky in appareance. Id suspect water, but there didnt seem to be any separation (water sitting at bottom, coming out first), also zero evidence of rust.... no redness at all
Now, my truck is an 03, shows 1200 miles on it (bought from GP as a runner last year), no cab / doors... AMK25), been going through changing fluids among other things. Some of the fuids, like transmission, looked new, filters had 03 dates on them so prob original.... but some of the diffs showed some water and at least some light rust (all the hubs looked good tho, no water... but there also was some evidence they had possibly been drained / refilled before). Anyways. Just some info on my truck, thought id pass along in case it helps someone else
