Thanks JD, bookmarked the link. Looks like place to go if / when I need to replace. It is interesting reading up on sludge build up the 4.7's generate. When I looked at truck I pulled oil filler cap and noticed some build up on bottom side, but went through records showing proper timely oil changes, thought maybe it was type of oil used, owner said to have used mobil 1. Grizzly thought about 5.7 deal but those days are over and that ford is another story.... that 5.0 makes noises I've never heard from an engine before, makes my old solid lifter hemi's sound quiet. Funny thing is, truck runs very very low 14's not bad for a stock 4x4. Truck quality itself is terrible. The whipple and very safe daily driver tune high 11's. with cheap insurance.... Happy Holidays