What is the significance of ONR?
For satisfactory operation of a gasoline engine (without engine knock) it is important to use a gasoline with the Octane rating for which the engine has been designed. As the new engine accumulates mileage, combustion chamber deposits (CCD) are formed and they continue to increase until they reach equilibrium after 10,000 to 15,000 miles. The CCDs result in an increase in the octane number required (ONR) for the satisfactory operation of the engine. For a typical gasoline engine, the increase in ONR can range from 4 to 8 octane numbers. Vehicle manufacturers compensate for this increase in ONR by detuning their new engines for lower octane gasoline so that after 10,000 to 15,000 miles when the ONR is stabilized, the vehicle may run satisfactorily using the commercial gasoline available in the market place. If DurAlt® FC is consistently in the marketplace fuels, the ONR can be minimized. In that case, new vehicles can be tuned by the manufacturers to perform at lower octane resulting in
