To make the Duramax 6.6L and its fuel system compatible with B20, GM upgraded some seals and gasket materials to withstand the ester content of biodiesel and included an upgraded fuel filter that includes a coalescing element. It improves the separation of water that may be present in the fuel, because biodiesel can attract and absorb water. Also, additional heating of the fuel circuit was added to reduce the chance of fuel gelling or waxing that could plug filters.

The Duramax 6.6L’s diesel particulate regeneration system features a downstream injector that supplies fuel for the regeneration process. This greatly reduces potential oil dilution, important with using biodiesel. Downstream injection saves fuel and works better with B20 than in-cylinder post injection, according to GM.

Extensive testing and validation was performed on the Duramax 6.6L using B20 that meets ASTM International’s standard D7467, which covers biodiesel blends between B6 and B20. The Duramax diesel is covered by GM’s five-year/100,000 mile powertrain warranty.

The new Duramax will power the redesigned 2011 Chevy Silverado and GMC Sierra heavy-duty pickups, as well as the Chevrolet Express and GMC Savana full-size vans. Chevrolet will unveil the 2011 Silverado heavy-duty trucks at the Chicago Auto Show on 10 Feb.