Call Lexington Paint Company. They have great customer service and I found them very helpful. If you need a lot of paint you can also order directly from them. They have 55 gallon barrels of paint available but we just had them ship use the 5 gallon size, as we didn’t want to handle the 55 gallon stuff. We needed 17 of the 5 gallon buckets to complete our project and we didn’t want to have to worry about trying to source that through Tractor Supply. It also came out a bit cheaper to get it from the paint company.
We used Lexington’s Fence Coat paint and it looks great. I had originally though we would use their Fence Pro paint, which is more expensive, but Lexington Paint told me that for my application the Fence Coat would do a better job. It is an acrylic paint, so is a pain to deal with when painting, but it looks great and the new paint is sticking like glue. I have a few spots where the horses put their teeth on the newly painted fence and I was happy to see that the black paint did not come off the old white stuff. There are spots where the horses chipped it down to the bare wood, but no white paint shows. I think this is a good indication that the new paint will hold up well.
We did do a lot of prep with our white fences. Power wash and sanding were done before painting. Good luck with your project. We are thrilled with how ours turned out.