This subject comes up on most Machinist groups and Metal working forums with annoying frequency, to the point of irritating regular members. Its a perfectly natural question for any new machine owner to ask; we all want the best for our machines. The discussion usually degrades into name calling because one guy uses chain saw bar oil for way oil, and another guy uses only the “factory specified” oil. I have never seen any five machinists who could agree on what is “the best” oil for your lathe.
To put this all into perspective, I’ll quote from what many people feel is the Holy Grail for oil selection; South Bend Lathe Works publication : How to Run a Lathe;
“ANY OIL IS BETTER THAN NO OIL”.
Many people will not deviate from the specifics in this book at all. I think it is important to remember that alot of this info dates back to World War One (technology has changed some), and most of our lathes predate World War Two. With the advent of synthetic lubrication and the wear associated with years of use, the picture might have changed a bit since How to Run a Lathe was first published.
When I was just starting to sell oil here in the
I talked to alot of “real” machinists, and Home Shop Machinists to get their opinions. I came away pretty confused, no one seemed to agree. When I told them I was using Mobil Vactra Way Oil, and Mobil Velocite Spindle Oil, and they would almost all say “Oh, thats about the best stuff out there”. Come to find out, every time I came across a well maintained machine, there was a can of Mobil right close by.
Everybody has run out of there favorite oil at one time or another, and used motor oil to lube their lathe. This might be alright in a pinch, but not for the long term; motor oil has emulsifiers that keep contaminants in suspension, which is great for car engines that have filters, but really bad for lathes that run a precision ground spindle in a cast iron or brass bearing. Mobil Velocite Spindle Oil is a non-detergent oil that allows residual debris to settle into voids in the headstock casting, and out of suspension. It is available in different grades for different climates or RPM ranges. Most of my customers request #6 (a little thicker for older worn lathes), or #10 for higher speed running. I didn’t see any difference in #6 and #10 in my lathe. Velocite (or it’s “equivalent”) is recommended by many leading Machine Manufacturers to maintain their machines. fact is: These oils don’t have any real equivalent.
Way oil is just as critical to maintaining the accuracy of you machine. If the ways are worn like a sway-back mule, how straight do you think the lathe (or mill) will cut? most lathes/mills/grinders spend most of their service life cutting in a narrow area (lathes near the headstock, mills in the middle of the table). You can usually see where most of the work has been done on an old machine. Sometimes you can feel it with your fingernail. I would rather see a greasy, dirty lathe, with oil running off the ways than a nice clean DRY one any day. At least you know the one that has oil dripping off it is getting lubricated. Oil is cheap, lathes aren’t; use lots of oil, you won’t regret it.
I sell Mobil Vactra is the Way oil for a reason: ITS THE BEST. Most guys ask for Vactra #2 for lathes (horizontal surfaces) and #4 for the vertical surfaces on milling machines and shapers. Vactra has special wetting and adhesive agents to keep a uniform film on your machine, and not dripping on the floor. It doesn’t stink or drip like 90 weight oil, and is designed to be used on friction type load bearing surfaces (in short: this is what it was made for). I suspect that most guys are like me; they probably use twice as much Way Oil as Spindle Oil, as it sticks to exposed gear trains and lead screws, and doesn’t fly off.
I asked the same learned folks that schooled me on these oils about what to use in the saddle, and was told that if I offered Mobil DTE Heavy/Medium circulating oil, buyers would beat a path to my door. Well, that might have been an overstatement, but I tried it and like it very much. it improved the feel of the powerfeed clutch. I can’t say as I’ve noticed any other benefits over the Mobil 1 Synthetic Gear Oil I was using, but it sure is a whole lot cheaper, and has Rust & Oxidant Inhibitors (R&O), has anti-foam agents to insure an even flow, and has an ISO 68 rating (SAE 20 weight) that closely approximates what SBL called for originally (its just a tad thicker). Saddles are probably the most ignored area of the lathe (kinda like a cars transmission), so I don’t ever expect people to get all worked up about them, but I’m glad I flushed mine and used DTE, I feel like the clutch action is crisper, and it just feels good to have clean oil running in it.
I hope nobody Emails me to let me know I’m a fool, or tell me that XYZ oil is better; I’m sold on what I’m using as it has served me well. I don’t have any affiliation to Mobil Oil (other than selling it), I buy it because it is a quality product that I can pass along to other users at a reasonable price. I’ll try and add to this entry as more information, questions or products become available.