My main engine is the Volvo KAD32P ~ 2003 boat with only 250 hours on it. Prior to this last weekend I added some diesel fuel treatment that I picked up from West Marine, can't think of the name right now. Other than the stabil type of stuff for the off season, this was the first treatment i've done. I was amazed at what it did, added 3 more knots to the top end added to the GPH consumption. Questions ~ how often should this type of treatment be done and second what should I be running through my Yamaha 9.9 kicker?