i've messed around with it- anywhere from 50/50 mix, to 70/30 motor oil/odourless mineral spirits. with more mineral spirits, the chain stays a little cleaner, and it's easier for it to get into the chain, but there's less overall lubricant left over after the light stuff evaporates.

nice and cheap. apply often.

obviously, don't be mixing this stuff up in your closet with no ventilation.

also, you've got to get the cheap, no special additive motor oil, or the mineral spirits will do strange things to it.