There is a lot of talk about the oil for the old transmissions that have brass parts as ours do they say the best is to use a oil that is rated gl4 not gl5 or not gl4/gl5 . It is confusing but in our hood the oil is not available .I was thinking of using a synthetic in the transmission a motomaster from Canadian tire 75w/90 .the diff does not have brass parts so you could use something else if you wanted.
