Additives for off-road and static applications now account for more than 50% of what FAST does. Over the years, the variable composition of off-road fuel, encompassing at any time blends of gas oil, diesel and biodiesel has resulted in numerous operating problems. This has been further compounded by the rapid developments in engine and exhaust after treatment technologies. These trends are set to continue as the fuel supply industry evaluates various replacement liquid fuel options. The suggested move to 100% EN590 standard diesel (in the UK, for example) will not, as some believe, result in a universal improvement in quality of reduction in field problems.