The new Variable Fuel Management (VFM) software upgrade allows oil and gas drillers to adjust their specific site’s dual-fuel mapping calibrations to optimise performance for four different natural gas compositions, including CNG, LNG and two Btu levels of field gas, including up to 1450 Btu. This upgrade will help to better match the source gas to the corresponding dual-fuel optimisation table. American Power Group Corp. claims that S4000 customers are experiencing up to a 10% improved diesel substitution rate, which substantially improves their payback period, which is currently in the range of six to nine months, depending on the source gas. The VFM upgrade is in addition to recent display upgrades, as well as new telematics remote monitoring capabilities.