I had my 07 CX-7 32K miles in for service and the dealer mistakenly put conventional oil in instead of the synthetic I've been running. Dealer says it's no big deal anymore... and I can bring it in next week for them to put in the proper synthetic. It will likely have 300 miles on this incorrect oil. I always thought once you went synthetic you should never go back ? Are there going to be any long term issues because of this ? Thoughts, concerns ?
Thanks.

 

Absolutely nothing to worry about, it's been decades (literally) since switching back and forth would cause problems. Unfortunately Old Wives' Tales persist and many folks, mechanics included, still believe them as if they were Gospel.

 

What he said..... ^ ^ ^