Here in Colorado if you do not use Penofin you do not get the job!!!! The elevation here in Denver is over 5300 feet and the suburbs are up to 8000 feet, so we take a beating from the sun(U.V rays),winter snow and summer heat not to mention how dry it is here.
Penofin works really good here because it is a Brazilian Rosewood oil base,it penetrates deep into the wood, hardening and stabilizing the fibers, yet allows the wood to breathe.
The only problem I have had it is very hard to work with.
Until a fews years ago you could only buy Penofin at the lumbers yards for 30.00 gallon, but since Home Depot showed up they sell it for 21.00 gallon
Jack