i have seen(i was told this was old school) a few that must have been submerged in warm oil for some length of time considering how far the oil had penetrated...( name brand maple) aside from being much darker then normal they were pretty nasty looking and dirty...i broke one up out of curiosity and set one on fire ofcourse

..burnt sooty like a pitch stick,heap big black smoke and a tall flame. only advantage i see was it was easy to light.