I am needing some help on which final gear oil to use. My owners manual says to use GL-4, but I am not having any luck finding it. All I can find is GL-5 and by what I can find on the internet, that is not compatable with GL-4 service. I have heard that it is ok to use GL-5 if it is a synthetic, however I can't find that on any manufactures web sites.
Do any of you know about this? I would appreciate the benefit of any research you have done. Thanks.