Re: using water on 6.0 powerstroke no water in oil
Double check your EGR cooler. They are trouble prone and even a two year old "updated" one can soon fail and leak coolant into the EGR/intake. I replaced mine with an aftermarket cooler. Make sure that the sharp point of the turbo mount stand (pass side front) is not hitting, and has punctured, the EGR. Some do and require a little grinding. Also, make sure your degas bottle, hoses or pressure cap, are not leaking.
If not the EGR or degas, and it's probably not if you used 2 gal of coolant, do a compression check. Sad to say, but it sounds like a head gasket.
Bite the bullet and do it right. Remove the cab (try that with an Excursion!) pull and machine the heads, and use ARP studs.
Other than the turbo and FICM (there are bullet proof fixes for those problems too), you will now have a reliable and good performing truck for many miles.
You can thank International/Navistar for keeping us 6.0 owners busy. Ford has already sued and we are part of the class action suit. Have you been notified?