Have a relatively high pitched whine that sounds like it's coming from the turbo/fuel filter area only on initial acceleration and only when truck has been able to cool down for quite a while or sat overnight. Goes away right after initial acceleration and cannot get it to duplicate noise. Truck was salvaged and my body shop guy and myself put it back together. Had 30k on it when we got it. Have 50k now, started this a few weeks ago, turbo seems to function appropriately and builds 20+lbs of boost according to the gauge. Recently towed me 30ft long enclosed trailer with a full house worth of stuff in it 1000 miles to Arkansas from Wyoming, so if the turbo was going out, I figured it would've let go there. Completely stock. First oil change I used motorcraft 10w-30, been using LE 5w-40 the last two. Checked fuel filter o-rings and what not, seems to be good.