I recently completed an outbuilding using treated plywood for siding. The wood appears to be dry. Would you recommend an oil or latex based primer? -Alan
I would use an oil based exterior primer (not the quick drying type, but a regular primer), followed by two coats of a high quality exterior latex paint. It’s also a good idea to add M-1 Mildewcide additive to your paint and primer if you live in an area subject to problems with mildew.
Good luck with your project,