According to the invention, there are provided motor fuel and lubricating oil compositions containing an octane requirement reduction amount of a compound represented by the formula: ##STR3## in which X is an oxygen or sulfur atom, R1 and R2 are hydrocarbyl radicals having from 1 to 3 carbon atoms, and R3 is selected from the group consisting of ##STR4## Particularly useful as ORR agents are: (a)