With the cost of diesel here at $3.19/gal, I thought of using biodiesel. $2.64/gal. Made with used cooking oils. Interesting info on different websites. Anyway, contacted the local truck dealer and asked if using it would pose any problems for my Chev W4500 (rebadged Isuzu NPR). He said that the manufacturer did not recommend it. So I shot off an email to Isuzu to get their response. Is anyone using biodiesel and if so, have you had any problems? What kind? Would welcome input from diesel mechanics. Mahalo.