wintersun's last comment proved to be true last summer when I got some bad #2 diesel (not biodiesel)in SD. My 2009 GMC Duramax gave no warning that we had a plugged filter and no warning about water in the fuel. My cost to get back on the road was over $9,000. If it's a fuel issue, GM won't cover the cost, regardless of the performance of their filtering system and warning system. I now have a pre-filtering system w/ boost pump (AirDog) because I know that the GMC warning system and filtering system doesn't work and the GM warranty is worthless in that respect.