Castrol Syntec is not a true synthetic oil. It is all a marketing scam on their part. If using a non-synthetic oil I don't think Castrol GTX is a bad product.

I had issues with a previous motor and while I can't prove it I believe the issues were related to my use of castrol syntec. I also have a couple of friends who believe engine issues they encountered were attributable to Castrol. In addition when the last generation RX-7 was undergoing testing a single synthetic oil resulted in engine failure. Nissan at the time took the route of stating that no synthetic oils were approved for the car. I have been led to believe the oil in question was Castrol Syntec.

I would not describe this as a Chevy vs. Ford thing. I would describe this as once bitten/twice shy, better safe than sorry. There are a number of good oils out there. Personally I am a huge fan of Redline oils although I have yet to use it in the car.