The F150 is the telecaster of light trucks, except that some of them have an Achilles heel. I have a 2005 Ford F-150 with the 5.4 liter 3-valve engine. 190,000 miles. It has been plagued with the common problems with the timing system, which uses oil pressure to activate solenoids that adjust the valve timing by adjusting the camshafts. About six months ago, I paid a good mechanic to replace the timing chain assembly, including the cam followers and VCT solenoids, with genuine Ford parts. I bought the truck five years ago with about 170,000 miles. I don’t know anything about its history. It only gets driven about 500 miles a month, sometimes less. At the mechanic’s advice, I changed the oil 1,000 miles after the repair. The mechanic told me that the tolerances in the bore for the piston in the VCT solenoid were so close that oil contaminants could still cause the VCT solenoids to malfunction. After another 1,000 miles, this appears to be happening, causing a very rough idle and a P0012 code. I’m considering an engine flush, done by an mechanic or oil change place. I’ve heard that doing so could mobilize lots of old sludge, possibly clogging oil passages and potentially ruining the motor. I’m looking for experiences, good and bad, resulting from engine flushes, using Seafoam, BG, and other products that use solvents. Has anyone experienced a disaster from an engine flush?