Yeah, it does smoke. Mechanic at my summer job put it in the tractors once a month. I didn't even know it could go through the vacuum lines, I just know it's over in the "fuel additives" section at work, where every product just goes in the fuel tank. I had assumed that you just took pics of yourself adding it into the fuel tank, then adding gas, and calling it a project (there are projects easier than that) so I was just being sarcastic. You know what happens when you make an assumption; you make an ass out of U and Umption...:lol: