I too have never replaced a car or engine due to a bad engine using regular petroleum oils where I maintained it since new (2000 mile oil changes) but I finally switched to Amsoil with two of my older cars, both with new engines (both cars were bought used, one already had the new engine, another had very high miles with previous neglect from past owner). Being that both cars are very well maintained, perfected, I wanted the best engine oil I could buy too, no need to skimp now. I've research Amsoil and have seen how well it keeps engines internally clean for years too on customers cars so it impressed me. The highest mileage car of these two cars is also a turbo engine (rebuilt turbo) so synthetic is far superior for turbo life.

I don't go as long on change intervals as I probably could (paranoid perhaps) so it does cost me more but I'm not easy on my cars so I like knowing I'm using the best oil I can for them. I'm so far not using sythetic ATF in the auto trans car but might in the near future.