Anyone running 18% oil that's concerned about oil content, just throw 4 ounces of Klotz synthetic oil in a gallon. That'll get you up to 20.5% Works for me. I took a plastic thow away cup, measured 4 ounces of water in it, marked the cup with a magic marker and that is what I use to add oil to my gallons of fuel. The 20% oil is important, the extra nitro is just a luxury.