Reduce, Reuse, Recycle. Here’s how to make wood stain using old motor oil and diesel AND an explanation for a few questions too. No, it’s not more flammable and it’s not bad for the environment. Yes, it’s smelly and slippery for a little while, then it’s not. And one I didn’t get to in the video: NO, you don’t need to apply to the bottom (you can if you want) but the bottom is not exposed to direct sunlight, likely less wear on the bottom of the boards, and water and snow don’t settle or sit on