i sold my 86 sdl to my girlfriends kid,the only fuel i ever ran in it was bio. he on the other hand would buy his fuel at wal-mart.within about a month his delivery valve seals started leaking.i told him to start running bio.but the only place here in town you need a fuel or credit card.so for the last 3 months he pays me and i use my card.within a week the leaks dried up.so i don't care what people say about ulsd not being the issue.i know it is.