My dad has an '06 2500 5.9 Cummins and a week ago it started running like crap. It would bog down if he gave it too much gas. He took it to the dealer and they said the lift pump went out. Upon further investigation they found the entire fuel system (gas tank, fuel lines, filter...) was cloged with a jello like substance. They called and him and asked what the hell additives he has been using. His truck is stock and he uses no additives. He mostly uses Shell Diesel. What could have caused this? Could it be 20% biodiesel that Shell uses? The lift pump was under warranty but the fuel system cleaning cost over 500$. I'm tryin to do some research to help him out so this doesn't happen again. Is it a Shell problem? I'm scared to put Shell gas in my hemi now.