I recently bought a '94 E350 with this engine. 70K actual miles. I have the OM for the van, in which Ford recommends a 5W-30 for all conditions for the 351, while a 10W-30 is recommeded for the 300 six, the 302 and the 460. Is there anything to watch out for with this engine? FWIU, this is a pretty stout and solid design and although it has decent power, its specific output in this application isn't all that great. Fuel economy seems a little better than what I would have expected from this hefty beast, although that's based only upon how quickly the fuel gauge needle has moved to the left over the 120 or so miles I've driven it thus far. What can others who've had 351Ws tell me about this engine?