I often make up a quantity of some oil finish by combining the dregs of other things just to get a usable quantity, however for the most part I use Liberon finishing oil if I want an oil finish. However, you can bung in oils - mainly tung and linseed (go for boiled if possible - raw linseed oil takes forever to polymerise), resins, varnishes and turpentine or mineral spirits with more or less gay abandon as long as you test the qualities and if need be add some Japan driers to make sure it goes off this side of next week.
I like to use a piece of clean glass, make a thin, penny sized puddle of oil on the glass and note the time it takes to set and also note the clarity, colour and hardness of the resulting film. I do this too if adding any stains to oil finishes, to ensure that I am not going to be disappointed when it goes on the wood.