My how times have changed, back in 2005/6 I had a Duramax and GM did not want you running biodiesel or anything above say B5 or B10. We had a few Biodiesel facilities around the Fort Worth area. It was made mainly from Soy. Had an instance where I ended up with what looked like tribbles in the fuel tank...so something didn’t react well. After $600 at the dealer to diagnose and flush the system I stayed away from biodiesel. Now many people have not had issues with it. Anyway, B20 is Diesel mixed with 20% biodiesel.