We loved our 2010 Ecoboost Flex, the love affair ended at 146,000 miles when the "check engine" light came on and the misfiring started 500 miles from home. The Ford dealer in Canada told us that one cylinder had no compression and another was at 50%. The original factory spark plugs had never been replaced and as a result we now needed to replace the entire engine for $6,500 and wait a week for the repair.
Our local Ford dealer disputes that spark plug failure could cause engine failure. We had them service it every 7,500 miles for all oil changes, scheduled maintenance and repairs since we purchased it new. Our assumption was that a Ford dealer would follow the Ford maintenance schedule. It was a bad assumption. The schedule calls for replacing platinum spark plugs at 90,000 miles. Apparently our dealer takes the "if it isn't broken, don't fix it" approach with regard to spark plugs. An expensive philosophy when maintaining turbo charged engines.
This is our first Ford. We have owned Volvo's and Honda's for the thirty years. Based on past experience a well maintained car should provide 250,000+ miles with minimal trouble. Lessons learned:
1) Turbo charged engines have a relatively short life span
2) Ford dealers do not follow the Ford maintenance schedule outside the warranty period. Ensure that ALL scheduled maintenance is actually performed.
3) Want high performance, great gas milage, and excellent reliability? Save up and buy a Tesla