I've switched to this oil from Castor 927. It is really clean burning. I like the fact that one bottle mixes 32:1 with 4 gallons of gas. I also like that it turns your fuel blue when mixed, so there's no question that it is mixed. With Castor, the fuel doesn't change color. No plug fouling, excessive smoke, etc. This is a really great product. In fact, I have switched to all Pro Honda products in all our bikes. They make really great stuff.