I've been using the #131 for a while now with great results, much better gas milage and the truck runs very smooth and is a little more responsive. Latley I switched from 92 octane to 87 and 4oz. of #131 and the gas milage stayed the same, in the past when I switched to 87 the truck went right through it,like 2-3mpg difference.The neutra #131 is a great product.