Ford says that the max sustained is 230 with a temp spike of 248, but I've also seen a general rule as follows:
175o= 100,000+ miles, 190o= 90,000 miles, 210o (Pressure Drops) = 55,000 miles, 230o (Valves Stick) = 25,000 miles 250o (Varnish Forms) = 17,000 miles, 270o (Seals & Clutches Burn) =...