Greasecar veg oil question

am thinking of selling my gas guzzling ford f-150 (13 mpg) and buying a
diesel guzzling Ford Van E-350.....and  collecting waste veg oil to use
for
fuel....there seems to be two options..

1 The Greasecar option - install separate tank, heater, hoses,  for veg
oil
.......I am not mechanic, so could cost 1500 to 2000 dollars.

2 The Diesel Energy Secret option - mix secret formula addative with veg
oil
and then just dump into fuel tank.....seems much easier & cheaper.

does anyone have any knowledge  or advise about these systems??  or is it
complete waste of time and money?

TOA