I've been using a light oil, with my ol' trusty Barbasol for a few years now. I try to use it every time I shave, but sometimes get a bit lazy and, just lather up, but when I use the oil, it does allow the Headblade to glide more easily. I use the CVS oil, a knockoff of the more expensive Neutragena body oil. Personally, I think the CVS oil is lighter, thinner, and about $4 to $5 less than the Neutragena oil. Smells nice too, (especially when the bride applies it to my 'bod', best when it is warmed, but that topic is foder for another thread.)
Earlier someone said they use baby oil, and yes, while inexpensive, it is nothing more than mineral oil with 'Johnson baby butt' smell added. And Mineral oil is less expensive than baby oil. I would suggest that if you want to try an oil, give the CVS oil a try. If ya don't like it, well, as mentioned above, there are alternative uses. The wife likes it too, in her bath, and, uhh, umm, applied by a willing partner.