Quote:
Originally Posted by supertrooper
The manual calls for “straight mineral oil gear lubricant”. I am not finding any locally. Does anyone know if there is a modern replacement for this?
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Any non-synthetic gear oil will work. For your latitude, a viscosity of SAE 75 to 95 will work. By ''Straight'' they seem to want a single viscosity, not a multi grade. SAE 90 might work. 80W - 140 would be good for the Desert Southwest.
Also if you have an SM 420 transmission, with brass synchros, you want service GL-4. GL-5 has additives for limited slip [Positraction] but these additives attack brass synchros.
''Mineral Oil'' refers to natural petroleum oil, not Synthetic. In 1967 synthetic lubricants were rare. Much has progressed in this field since then, but if you want to go by the book, avoid them.