I just recently was told that my 2006 VW Beetle was to have had synthetic oil and not regular. I have had the oil change professional, but in between I have added regular oil (not knowing what kind they used). I always ask for and put 10W30 in my car so I added regular instead of synthetic. Will this hurt my engine? I know now and will only use what I am supposed to. Thanks for your responses.

 

If it is the same grade it will not hurt the engine. By law, DOE has required that all oil of the same grade be compatible with all brands, synthetic or mineral. Just don't mix different weights of oil in the same engine except in case of emergency and only for a very short period of time.