With tighter emission control, the removal of sulfur from the diesel fuel today also results to the loss of its natural lubricity and other protective properties the consequence is early failure of the injection system and the diesel engine itself.

The oil companies claim that lubricity additive is pesent in their diesel fuels but fleet owners and farmers in the US which depend so much on their 'diesel machines' had already bad experiences and don't want to gamble so they personally add a lubricity additive to their diesel fuels.

According to U.S. or European studies, the addition of at least 1% biodiesel to diesel 2 and at least 2% biodiesel to diesel 1 passed the ASTM wear scar diameter (WSD) standard on injection system. Biodiesel posseses excellent natural lubricity property.

Take note however, that wear reduction is observed with non-distilled biodiesel, no significant improvement in WSD was observed with distilled biodiesel. So ingat as to what biodiesel are you using.