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Bridgeport mill spindle oil. Velocite #6 or #10?


I have been using Mobil Velocite #6 oil in my 2HP series 1 Bridgeport mill for 20 years with no problems. I was recently told that is the wrong oil and I should be using Velocite #10 which is a little bit thicker oil. Searching the web, there is no definite answer. Even business specializing in Bridgeport mills and selling service, parts and oils, are different. Some say #6 and some say #10.

Just curious as I see no need to switch after this many years but am wondering what Bridgeport recommended. As all the mills they make today have sealed bearings, there is no info on their web site as to what to use. My Bridgeport service manual says Mobil DTE 32 oil which is a hydraulic oil.

Greg Menke

Active member
I've used both- ordered some #6 by accident, worked fine but quickly runs thru the spindle. #10 stays around a bit longer. DTE 32 would be fine too, though I tend to use that more on the lathe.


New member
Agree with Greg, either is fine if you fill them up each time when used..the #6 runs tru quicker. I also use the #10 in the southbend journal spindle bearing cups for the same reason


Active member
Bridgeport mills have ball bearings with preload.
Not like a jig borer, but some preload.
Unless you run 3 or 4000 rpm,
you do not need thin oil.
If you use ISO32 oil and the spindle does not
get hot, this is just fine.
If you are running 3 to 4000 rpm and using
tiny end mills or drills, and the spindle is
getting hot to the touch, then maybe use the
thin oil.



Active member
At the instrument shop we used 30wt engine oil, those machines wereat least 30 years old and ran great.

I'm not convinced it matters all that much.

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