this stuff works wonders on a 7.3 too!
there isn't much around about people using rev-x in their 7.3's, just 6.0's.
i have an '03 7.3 that has had startup issues when sitting for 3 days or more, sometimes less. it would crank for a minute before enough cylinders would start firing just enough to keep the engine turning and then it would take 5-10 minutes before it would start firing on all cylinders.
i changed the oil, added 2 bottles of rev-x, my brother drove it around for a week, i let it sit for a week after that, today it fired right up on all cylinders like it wasn't even cold. it even runs much better while warm with better throttle response.
i've always though oil additives were a joke..... most still are