Chet, the tag on the back of my 612 recommends a 150-225 SUS @100*F way oil. The Harrig manual very strongly suggests that you use their way oil in order to prolong the pump and the ways. I just use Harrig Way Lube #16211245 as it isn't all that much more expensive. Replacing the pump is expensive. If you call Harrig in Elgin Ill., ask for Jim Seyller. He is very knowlegable and helpful. He can tell you anything you need to know about your machine and get your oil ordered for you. 150-225 SUS would be comparable to Vactra 1. Harrig can be reached at 1-847-695-1000. Doc
I called Harig about a year ago concerning a substitute way oil in their machines. They claim there is no substitute for their oil. Regular way oil will gel up and not pump through the system.
I have ran Harig surface grinders for 25 years at work and now have my own 6x12 in my garage. They are built 20 miles from home in Elgin Illinois. In fact Jim Seyller and I know one another from High School.