Cresote is no longer available to purchase over the counter and is only available to purchase under license by fencing contractors. What you get now in your farm supplies is a cresote substitute which is nowhere near as good as the real thing. The long life fencelife by Ronseal is probably as good as whats out there. It is supposed to last up to 5 years but depending how exposed to the elements your fence is, you should get a couple of years out of it.