I don't think I've ever seen white smoke out of the rocker breathers that had anything to do with coolant in the oil. Coolant usually settles under the rocker cover in the form of white slime because the rocker cover is still cold and it condenses and emulsifies there. Once it is warmed up, it is probably invisible vapor. I think all he has is blowby which really doesn't hurt anything. Our preferred way to get rid of these fumes was to plug the breather and run a line from the breather to the top of the air cleaner. This way we didn't have to worry about a PVC sticking and causing a vacuum leak and it kept the fumes out of the cab.
