I've used 3 gallons of KILZ Premium Primer (2 coats plus touch ups) and will top it with Behr's Premium Plus, Paint & Primer All in One, Exterior Satin Enamel in a Medium Base. Please don't tell me that many coats of primer is not necessary and that the Paint & Primer combo is overkill, because my goal is not to finish the job asap, but to get GREAT coverage that will last as long as possible. It's worked very well for me in the past, just can't remember the approx. ratio. Thanks.