I installed Evans in my truck several years ago. I used slightly less than 7 gallons. I bought 8 and still have one left. With zero pressure, you want to keep the coolant level on the low side because it expands more than when under pressure.
For what it's worth - I flushed my system with 15 gallons of distilled water before installing the Evans. I got quite a bit of grit out. I did not install a filter and my Evans looks as clean as the day it was installed 37,000 miles ago.
Evans is great stuff IMO. /ubbthreads/images/graemlins/smile.gif