O'Donnell is a brand of nitro fuel specifically blended for R/C cars and trucks. The brand is distributed by DuraTrax, a division of Hobbico. Marketed to racers and highly respected in racing circles, O'Donnell fuel has become a popular choice with sport users as well. Its unique base, a blend of both castor oil and synthetic oil, makes for smooth idle and acceleration. The base is roughly equivalent to an 18% standard lubricant blend. Other additives aid in thermal stability, an important consideration not only in regular use but in storage as well since hot ambient temperature tends to degrade most fuels. Unique anti-foaming agents are used to prevent the formation of air bubbles in a pressurized fuel system which in turn lead to a too-lean condition.