I think we're about to find out how well hydrocarbons work in 134a systems, and not just from you. Still, don't mix the gasses and be sure of the oil miscibility. Your car came with PAG oil.

If you use hydrocarbons, do not "release" some of the vacuum before charging. You don't "release" a vacuum. Instead, the act is letting air in. Air contains moisture, and moisture will polymerize with the oil.