Fat Cat Oil is unlike other valve oils on the market.  It is a organic (“dino” oil, as motorcyclists call it) blend in the same viscosity range as Al Cass, Yamaha, Zaja and others, but far outperforms them all. Why?  Laboratory tests show that Fat Cat Oil contains far fewer impurities than other oils, since it uses cosmetic grade oils as its base.  This contributes to the smooth valve feel and lack of smell.  Some valve oils on the market add anti-foaming and wetting agents to their oils.  Fat Cat does not dilute its oil with additives. Once I owned a quart of a well known music store’s brand oil- I didn’t use much of it, but noticed that after a year, it had started to turn an unpleasant yellow color because of the impurities within the inexpensive oil.