 The engine completely blew on the car and had to be replaced, at a cost of $13,000.  The car still had $18,000 left on the loan and was blue booked at about $21,000.  Ford dealer said that since I was late on an oil change (by about 4 thousand miles), that caused the failure. They said when they went to drain the oil, it was thick and black and that is what caused the engine to fail.  I said BS, the  engine, in the process of failing, CAUSED the oil to become black and thick, because there is NO WAY that missing one oil change by only a few thousand miles can cause anything close to that kind of damage.Bottom line: I paid for the new engine then DUMPED (sold) the POS as fast as I could.I have had great experiences with Ford trucks going back to the 90's.  I think this may have been simply a LEMON, but the dealer didn't give a crap.Believe it or not, I replaced the Flex with a 2015 F150 with ecoboost engine ... we'll see how this goes.The AWD transfer case (part of the transmission) fails on these cars!  Cost $1,600 (with labor, the part is about $1000) to replace it ... that is IF they don't find other issues due to RUST on the parts that have to be removed to replace the transfer case.  In my case: the right side control arm had to be replaced because they could not get the ball joint to release, so the ball joint got ruined in the process AND since Ford in its quest to save FORD money has front control arms with the ball joints built in and not replaceable means that  bottom line: ball joint (a $20 part) fails, you end up buying a $200 control arm and paying $100 in labor to change it.  So now we are at $1,900.  Next is the passenger side turbo charger .. it is located forward and low on the engine and has no protective covering or anything to protect it from the elements, so it RUSTS  - badly!  It has to be disconnected to replace the transfer case. The mounting flange and bolts rust so bad that they break when attempting to remove.  Now we are buying a new turbo charger at $586 plus $560 in labor!  So NOW, the cost of replacing this transfer case is a whopping $3,046!!  My advice: if your Flex is going over 60,000 miles GET RID OF IT!!