Field of the Invention
Lubricating oils used under the severe conditions of diesel and gasoline engines are highly compounded so as to neutralize acids derived from the oxidation of sulfur in the fuel and from partial oxidation of hydrocarbons, both from the fuel and oil; to disperse sludge- and varnish-forming precursors within the oil; and to inhibit oxidation and wear; as well as enhancing other lubrication properties of the oil. In addition to the requirements normally attendant to a diesel and gasoline lubricating oil, those oils which find use in railway diesel engines have the additional factor of not being corrosive or reactive to silver. Silver bearings are used in a preponderant number of diesel railway engines today.
The desirability of having a single additive providing multifunctional properties is evident in the efficiency and economies in the manufacturing and using of a single additive as compared to a plurality of additives. However, because of the severe operating conditions under which a lubricating oil performs in diesel and gasoline engines, it is frequently found that additives, while effectively performing a particular function, will tend to degrade and enhance deposit formation. Therefore, in designing any particular additive, it is essential not only that it fulfill the functions for which it has been designed, but that it be stable under the conditions of use or degrade slowly to materials which do not enhance deposit formation.