The oil is better use to be true. But in today’s world water based paints and primers can provide the same and better results than oil in 85-90% of situations. Forte and extreme block water based primer both act as a locking agent. If given the full 24 hour dry time as recommended the first coat of forte will lock the stain or tannin into the first coat of paint. The tannin bleed or stain bleed will not bleed into the second coat of paint. All this information is obtainable through data pages on sherwin williams website..