SErious questoion about mediums?!?!?!?1?

This is for oil painting, what is most commonly used for oil painting? IN the begginning, i've uses that liguin original stuff, they i used linseed oil. normally I just use the liquin original, but I was wondering what is mostly common to use for the medium? What did the old famous painters use? LIquin original? LInseed oil? Refined Linseed Oil? Or something else? Thank you so much for your answer!!