+2 on the K-100 this stuff works great. I use it in 4 o/b's , mower & 4x4. It breaks down the water so it will burn. They also claim it boosts the octane up to 2 points. Google their web site & watch the video. I saw a demo. at a sm. engine repair shop & it really seems to do what they say. A bit pricey but it works for me.