Isuzu Australia’s product planning and engineering support manager Simon Humphries said the variety of processes and feedstock being used in biodiesel production could impact on truck performance.

Humphries called for biodiesel blends to be mandated to a maximum of B5 (5% biodiesel) and inspections to ensure the product met national fuel standards.

"This would be good for the biodiesel industry and offer some level of security to end users who don't want to risk engine life, efficiency or running costs," he said.

"At this stage the long term effect of biodiesel on engines is unknown. As a result Isuzu, for instance, does not approve of the use of biodiesel blends above 5% [B5] in its engines," he said.

"Australian authorities need to be on their game to ensure biodiesel meets fuel quality standards in the manufacturing, storage and blending processes."