摘要 |
A method for monitoring the performance of a compression-ignition, internal combustion engine which method comprises lubricating the engine with a crankcase lubricant, and introducing a fuel to the engine to operate the engine characterized in that the fuel comprises greater than 50% by weight of petroleum-based, middle distillate fuel oil and/or a Fischer Tropsch derived middle distillate fuel oil and 2.5% to 25% by weight of at least one lower alkyl ester of a fatty acid, and the performance of the engine is monitored by measuring the rate of ingress of lower alkyl ester of a fatty acid from the fuel into the crankcase lubricant by infra red spectroscopic analysis of the crankcase lubricant. |