clay how to warm

I often use a crock to warm my clay, the type for turkeys -larger , then I keep an aluminum type tin inside, and put the clay in this. To keep clean or if I need to use another clay. You need to keep low heat, try different heat settings to see which works best for you.
You can heat in a microwave -be careful, you can burn your fingers.

oil based clay to use

I use Klean Clay for my sculptures. You can order at sculpt.com or other places. I order directly from the company that makes the clay.
Reason for this- I use grey clay-ex-firm, You cannot buy the grey clay in ex-firm unless you ask for a order from the company, you have to buy 350 lbs.
I think it is worth it for the money you save in the long run.
You of course can re-use the oil-based clay over and over again.