No prob mixin. I mix oil with water base even. Seems oil helps keep crystals from water base from cloggin pins. Acts as a lube. Far as pain depends on brand I have test prop 100-150mg homebrew that painless. Make sure to try and get oil as close to body temp before inj and push slowly. 2cc inj should take 1min to push this will help with any pain. U can hit muscle you gonna work I would say do inj in the morning push slow and massage 2-3 min soon as you done inj should handle about all the pain