I have an old RobinAire AC vacuum unit that will spray a fine mist from its exhaust. I keep it out of the shop air by keeping a wad of steel wool in the port. It allows plenty of air to pass and captures the oil.
Oil vacuum pumps last longer and usually pull higher vacuum. You don't really need the level of vacuum needed for refrigeration when vacuum veneering or holding parts, but a high cfm will overcome small leaks and pull the air out of your vacuum bag faster. Air is being pulled out, so how is oil to get into your vacuum bag or chuck, unless the pump suddenly stops and leaks backwards. I am more concerned with pulling sawdust and debris into my vacuum pump than oil going backward from the pump to my project, so I use a filter in the vacuum line to prevent this. On the exhaust coming out of the vacuum pump, I also have a filter. This one is one of those orange disposable filters like used for spray painting. I don't replace it after every use, but do replace it frequently. It keeps the oil mist out of the shop air very well.
I have not thought about the oil mist in the shop.... my friend that I turned with before he had to give it up due to health, had a fully enclosed shop on a concrete slab, so he did have an issue with the oil mist.... my shop is an enclosed metal building, but with lots of air circulation.(corogated tin roof on the wall headers... lots of daylight over the walls.... my lathe sits half in the door way of a 6' wide double door way and when I hook up the vacuum pump, it's sitting in the doorway which is usually open.... and I always have a fan running that blows out the door... probably not an issue for me.