Not to continue to drag this thread off topic, but I stumbled upon this discussion on accident. This 5W20/5W30 topic was hashed to death over at another forum I'm active in. I wouldn't be surprised if Ford went back to 5w30 on the V10s. When my truck was new (early 1999) the original owner's manual specified 5w30, it was only later that they revised their recommendation to run 5w20. I'm currently running 5w20 in my truck but I don't think 5w30 would hurt either. I find 5w20 convenient though since that is also what my wife's car uses. So I just buy Motorcraft 5w-20 for both vehicles.
As far as engine life, there is an invidual on that other forum that services a fleet of E-350 V10 vans (airport shuttles I believe) and he has many that have close to or over a millions miles with only oil changes and normal servicing. Comparatively my V10 is barely broken in with just over 90k miles on it (all without a single blown plug
), but I'm sure the V10s in your motorhomes are always working harder since most of my miles are with an empty truck.
Personally I love my V10, even if it is an early 2 valve version. A diesel would pull better, but I have almost the same amount of torque and more horsepower than the same year powerstroke. I'll admit I would prefer a diesel when I'm towing especially above 6000 feet, but my truck sits a lot and diesels don't like that, the V10 can sit for months and fire right up every time. That's what makes it a great engine for motorhomes IMO if you aren't a full timer.