Al, I can't tell you anything about mill gearboxes but (to the best of my knowledge) the only difference between ATF and SAE30 is that ATF works well with the clutch packs inside a automatic tranny. If motor oil was used in an automatic, the clutch packs would slip. Considering how low tech a mill g/box is (they have neither synchro rings (manual) nor clutch packs (auto)), I can't see a problem running either. As for the claim that ATF offers superior protection for the gears, I very much doubt it. So with that in mind and also considering it is significantly more expensive, I wouldn't bother. |