I used all 4 quarts but it would have been fine with 3. I had it so I used it. It has held up very well and am very happy with it. I have had many trips where desert pin stripes were guaranteed and there is very little evidence now. My sons truck has a couple of spots where it delaminated likely due to poor prep in that spot and not as durable in the bed as true bed liners. But for the price it is great and would definitely do it again. I strongly suggest you test spray some plywood to find your ideal texture, medium to low pressure with flow rate in the middle gives a smoother finish.