One of the properties of bio-diesel is that it INCREASES lubrication of all fuel related components. Whatever diesel shop told you otherwise is probably either dishonest, or just doesn't know what they're talking about. I ran B20 in my 98 C2500 for years without any problems (other than changing fuel filters more frequently at first). The injection pump was changed at 96K miles, well before I started the B20. It now has 237K miles, still running strong. I don't use bio any longer, only due to no availability. We use red diesel on the farm on all the equipment, not the trucks. It's about .50 cheaper than on-road diesel, so keep that in mind when buying mowers. Our JD 997 sips fuel compared to the Kawasaki's on the smaller mowers we've used. Also, be advised, the new (2011) Ford diesels (F250-F350) are certified to use B20.