I have recently acquired a 1956 m211 as my first deuce. Having read all threads I could find on the trans. oil it seams there are 3 options for the oil. So still not sure as to witch is best. Have downloaded the military manuals on the 211 and they say 10w engine oil. So I think the military would want a dependable vehicle sence a down vehicle could cost mens lives, Ill go with 10w engine oil. Am I wrong in coming to that conclusion?