Today I ended up with 1,420 miles on my cleaning phase. Since I had a little time I decided to go ahead and change the oil and filter and start the rinse phase.
This is on a 2005 Chevrolet Silverado 5.3L that I bought a couple of months ago. It only had 45,000 miles on it when I bought it. I found out it was a GM lease vehicle and soon started to realize it had probably had little to no maintenance done to it until I bought it. Since I started the cleaning phase I have noticed it runs smoother, quieter and the valvetrain clatter it had during cold starts is completely gone. I haven't checked the gas mileage since I started the cleaning phase. I will do that sometime during the rinse phase and see if there is any difference from the 15mpg it was getting when I bought it.
I opened up the oil filter and took a couple of pictures. They are not the greatest quality, but I will try to attach them. If I have the chance I will try to open the oil filter at the end of the rinse phase too.