So I had my oil change done today and somehow they used castrol full synthetic, I've been using regular castrol oil up until this point. I saw the bill and complained, ended up paying what I normally pay.

However in the future can I go back to using regular Oil with an engine flush?

I'm concerned about having possible engine probelms in the future, shouldn't they have flushed the engine before the change was made to syntheic?

 

No flush necessary - you can mix dino and synth with no problem. That's why they sell sythentic blend. There's no problem swithing back and forth.