Fred, my advice not to use synthetic oil to break in a motor is directly expereinced based, the idiots at Redline Oil told me I could break the motor in on their synthetic oil, I ended taking the motor back apart after one weekend and cleaing the bores and rings and reinstalling and then breaking it in on dino based oil, and I seen this happen to other guys at the race track as well. I have no idea what the new cars are using for rings and bore finish and for sure they are not using cast iron rings, so in short, you could hold a gun to my head and I still would not break a new British engine in on synthetic oil, for me it not a opinion based on something I read, it's a real life experience, one I'll never try again.