Test drove a well known truck dealer's 2011 Limited with just under 26,000...HD tow package. Some cosmetics, but overall very clean...including dipstick. However, the left side valve cover, the alternator, and a barely visible component (water pump?) just on the front right of the engine is covered with what appears to be heavy surface corrosion. The sales guy offered that it might be blow back from a leaky battery (you could see moderate deposits on the + terminal). I replied don't think so because all the tubes and lines on the left side would be covered with blow back as well...and they're quite clean (unless they were all replaced). Their inspection policy is my mechanic either has to come to them, or I buy the truck and then take it to my mechanic...yeah, right! I looked hard and the only drawback is that nasty looking engine. I own a '97 Explorer with an immaculate engine... Is this something that shows up on low mileage Expy's?