June 9, 2010I`m just in the process of breaking in my engine on my 2001 F-150. She`s only got 215,000 miles on her and has been as reliable as my previous Fords. Somethings happened in the last week or two. Sometimes, not everytime, I`ll get a puff of smoke (oil) out of the exhaust when starting. It`ll happen maybe once out of every 10 starts. I run synthetic since the day I picked her up, and don`t see any other problems except for a P401 code that came on last week.