Mobil 1 oil isn't what it used to be. Once they sued Castrol over the PAO is the only true synthetic oil thing and the courts ruled that Castrol's Group III dinosaur extract with pour-point depressants and coiled-polymer viscosity improvers was ok to pass off as the same thing, Exxon-Mobil gave up and went back to the much cheaper refined crude for their "full synthetic" formulas so they could continue to compete in the market at the same price point as Castrol, Valvoline, and the others, same as everyone else except for Amsoil, Motul, and Red Line as far as we know. Fiver and I have worked with several true, PAO base stocks and many other base stocks (PAGs, Monoesters, Diesters, etc.) and I can tell you that true PAO synthetics don't mix well with paraffin or microwax much of the time. Moral of the story, the majority of Mobil 1 oil isn't PAO-based (and thus will blend well with most things), and it isn't PAO, which means it isn't a truly uniform molecule with all the great additive-free qualities we expect from a synthetic base stock.
To thin your drawing wax, I'd buy a pint of automotive air conditioning ESTER oil at the parts house. It's used to retrofit Freon systems to Suva systems (R-134a) because it will misc with Suva refrigerant and also soak up residual Freon-compatible mineral oil left in the system. Ester oils will blend with anything organic, petroleum, or even PAG. The AC-grade stuff isn't sticky. If you require a little tackiness or want the added benefit of the EP properties of polybutene, you could thin your Castrol wax with any kind of two-cycle engine oil. I recommend Maxima K2 ester oil, Red Line (you can still get it on the West Coast I think) or Motul ester above all of them. Remember, the 2-stroke oils are about SAE 30-weight (ISO 100) and are thinned with something like naptha at 30-50% by volume so they will mix quickly with gasoline, so once the solvent evaporates your case lube will thicken. The AC oil won't do that, what you get is what you get if you use it to dilute the wax.