Is it bad to put synthetic oil in once and then switch back over to conventional oil?

I have an old carolla and put synthetic oil in it once but i've been told for a car like that its just wasting money to put synthetic in it so is it bad to switch back over to conventional?Is it bad to put synthetic oil in once and then switch back over to conventional oil?
It wont hurt anything at all.Is it bad to put synthetic oil in once and then switch back over to conventional oil?
I call bunk on that one. If 'they' say it, I'd like to know who ''they' are. From the Castrol website (if anyone would try to discourage you from switching back to dino oil, they would):





FACT or MYTH?


Once your engine gets a taste of synthetic motor oil, there's no going back to conventional oil.





Answer: MYTH! Synthetic oil is compatible with conventional and synthetic blend motor oils. You could go back to conventional oil, but you'll miss out on the superior engine protection only synthetic motor oil provides. You wouldn't go from DSL back to dial up would you?





http://www.castrol.com/castrol/genericar鈥?/a>
Ah, I just got my oil changed the other day and the guy was telling me I couldn't just switch back. So then I had to get the expensive oil change. Go figure. Anyway, he said I would have to have my engine completely cleaned out before I could switch back to normal oil. Something about those above-mentioned detergents screwing it all up and then if I were to switch it would erode bearings, etc. I don't know. He was making money off my ignorance, so good luck with this.
yes once you switch from a natural base oil to a synthetic you are not supposed to switch it back to regular oil they say that the detergent in the synthetic wont let regular oil bond back to metal like it supposed to
valvoline makes a high milelage half synthetic, half conventional, this would be a good compromise for you.