Oil for Headstock on Standard Modern Utilathe

Hello All,

I recently purchased a 9.5" Utilathe and the previous owner seems to have been running gear oil in the headstock. (I am going by the smell, gear oil is pretty distinct smell). The manual says to run SAE 30 oil for everything. Is there a reason I would want to keep using the gear oil in the head stock versus what the manual says?

Thanks in Advance.

The manual specifies SAE30 which is just the viscosity of the oil and this would be the same as ISO100 non-detergent oil. Note that SAE viscosity is confusing when it comes to engine oil vs. gear oil. So you would want to use gear oil, not motor oil. An equivalent SAE30 (viscosity) oil is something like Mobil DTE100 Heavy ISO100, I do not recommend differential oils or those with friction fighters or extreme pressure additives because it can damage brass bushings in some cases. So any ISO100 circulating/gear oil (farm tractor duty) will work, but if it were my machine I probably would go with an ISO68 gear/hydraulic oil, in particular if you are in a colder climate. These days most lathes specify ISO 68 for gearboxes, the headstock ISO 68 or for higher speed lathes ISO 32 circulating oil in the headstock. In the open gearboxes, like Norton I prefer to use way oil, Vactra #2 or Vacuoline 1409 which are both ISO 68 oils with tackifiers. Condensation can form in the gearbox and headstock, so even though the oil may look clear it should be changed every 6-12 months. Sometimes a small amount of kerosine may be added to the oil, the machine is operated for a short period and then drained to get out the sludge. This is outlined in your manual.
https://www.brwtechnologies.com/Vacuoline_1409_p/mobil_vacuoline_1409.htm

I quite agree, gear oils with EP additives should not be used in machine tool gearboxes, especially worm gears with bronze worms, it actually wears them out in a short time; the additive oxidizes the bronze and the worm rubs it off in a continuous process, and also, EP is of little or no value to ordinary gearing, it should be used only for high stressed gearing, such as spiral bevel or hypoid.

Thank you for the information. I thought i was good to go with non detergent SAE 30 oil. I guess I need to research some more.

Viscosity is just viscosity, but there are a bunch of ways to describe it. SAE 30, as specified, would be fine. However, it is often used to describe engine oil, at least in the U.S., and a lathe does not have an internal combustion engine. Hydraulic or tractor oil is probably the best bet without having to travel too far to find it or pay too much for it. ISO100, as mentioned above, is the viscosity equivalent of SAE 30. Being that you are in Canada, in the frozen north, ISO68 would probably work fine, and that is what most modern equivalent lathes use. ISO68 hydraulic or tractor oil would be a good choice, and likely available where you are.

Thanks for the information everyone.