Gear oil for Mill and Lathe

[pcarpenter]

What you put in is way too thick and will likely foam badly. ISO 68 hydraulic oil is just what you want and most any farm supply place should have it. As others stated, Mobil DTE is available via mail order.

Motor oil is not ideal (among other reasons) because it has detergent additives that keep dirt and grit in suspension. That's fine in a pressure lubricated system with a filter like an auto engine. Not so fine, on the other hand, in a lathe gear box where you want the wear by-products to settle out. Hydraulic oils have anti-foaming agents since they are moved back and forth under high pressures.....which tends to create air entrapment.

I am using Mystic (Citgo petroleum) ISO 68 hydraulic oil I got from the local Farm and Fleet in my import lathe. I added just a bit of Lucas Oil additive which helps it climb the gears just a bit (improves cling). It's far superior to the Chinese egg-foo-goo that came in it. It would produce foam on top that in cooler weather made it look like someone blew in some foam-in-a-can

Edited to include image link to ugly foam formed on top of Chinese lubricant:



paul

[rantbot]

"EP" (extreme pressure) isn't needed with spur gears. EP oils have additives for enhanced film strength. They are needed with gear types with significant sliding motion under load, usually hypoid or spiroid gears.