Sulphur

Sulphur occurs naturally in crude oils and must be removed to an acceptable level during the refining process as it promotes corrosion and affects the performance of vehicle emissions control equipment. While sulphur does not affect engine performance directly, it reduces the efficiency of catalytic converters. There is no performance or emissions effect on older vehicles not fitted with catalysts; however all vehicles with operating catalysts will show some emissions reduction with reduced fuel sulphur levels. The magnitude of the effect will vary according to technology employed, vehicle and catalyst condition and driving mode. State of the art exhaust after-treatment, currently offered on Euro 4 and Euro 5 compliant vehicles, requires significantly reduced sulphur levels for durable and efficient operation.