some of you may frown on this practice but it really does work. my grandmother is 96 years old and was born/raised on a farm in the countryside on the island of maui. there were few stores like todays island and the family was forced to make due with what little they had. they used old motor oil for preserving wood. it was painted on 2x4's or whatever and it repelled termites and rotting. over the years she has used this practice religiously when building things out of wood in the outdoor environment. like i said she is 96 right now and is very active in her little backyard garden with garden boxes and plant shelves(up the ying yang) and the wonderfull aroma of used oil.