I have made some biodiesel in the past and tested it using the 27/3 conversion test AFTER it was washed and dried only to find that the fuel was not completely converted to biodiesel. This means that some of the mono- and di-glycerides were not converted to methyl esthers. I chose to run the fuel in my 2002 Jetta TDI without re-processing the fuel and I ran it in the summer. Does anyone know what the reprocussions of doing this are? I mean, it's similar to mixing filtered like 5% WVO in with good fuel. So as long as it's warm out, this shouldn't be a problem....maybe more of a problem in a PD engine?? But what about the 2002 TDI's? Are they ok for this. I have heard that older mercedes cars can run on anything.