I've heard people say that before, but my experience has told me that it's usually not the synthetic that caused the problem. It's usually that synthetic revealed the problem, which is a gasket that wasn't completely sealed or had shrunken.
AMSOIL synthetic motor oils are made of completely pure, ideally-designed synthetic base stocks, blended with the highest-performance additives available, and are fully compatible with all engine gaskets and seal materials. In fact, because they are more painstakingly designed than petroleum oils, AMSOIL synthetic oils help maintain seal integrity better, rejuvenate shrunken seals, and extend seal life far better than conventional oils.
What I like best about selling Amsoil is that we have a Tech Services Department filled with people who are passionate about performance and quality. If you ever have a question, please feel free to holler at me or go straight to the guys in the lab.
https://www.amsoil.com/techservices.aspx
They usually answer within 48 hours.