Diesel fuel composition

It has now been found that certain specific oxygenates when added to cat diesel fuels can enable the particulate emissions from the exhausts of engines powered by these fuels to be substantially reduced when compared with some of the additives used hitherto with little to no NO x increase.
The cat diesel fuel compositions are not intended to include fuels which contain substantial amounts of olefins (e.g., greater than 40% by weight) such as those produced in some of the Fischer-Tropsch processes. The fuel compositions contain no more than 10% by weight of olefins, suitably less than 5% by weight of olefins and preferably less than 2% by weight of olefins. Such fuels may be produced by modified Fischer-Tropsch processes to control the olefins formed therein to below the threshold levels now specified. Furthermore, the base fuel used has less than 10% by weight of esters, i.e., the base fuels do not include the so called biodiesels.