A mixture of alkoxy-terminated poly-oxymethylenes, having a varied mixture of molecular weights, is blended with diesel fuel to form an improved fuel for autoignition engines. The mixed alkoxy-terminated poly-oxymethylenes may be produced by reacting paraformaldehyde with methylal, methanol, or other alcohol for a length of time and at a temperature and pressure sufficient to form the mixed alkoxy-terminated poly-oxymethylenes. The base diesel fuel, when blended with the mixed alkoxy-terminated poly-oxymethylenes in a volume ratio of from about 2 to about 5 parts diesel fuel to 1 part mixed alkoxy-terminated poly-oxymethylenes, provides a higher quality fuel having significantly improved lubricity and reduced smoke formation, without degradation of the cetane number or smoke formation characteristics when compared with the base diesel fuel.
David S. Moulton; David Naegeli