I've been lurking in the forum for a long time as I've been debating moving to a diesel vehicle to use bio. I witnessed DSE in action last night for the first time. Here is the process that was used:

Filter 40 gallons of used veg oil into drum #1

Pump that veg oil into drum #2 thru a filter

In drum #2, add 2 gallons regular gas, 4 gallons kerocyne, 7 ounces of the DSE solution, and 32 ounces of "clear diesel".

Pump drum #2 into drum #3 thru another filter. At this point the fuel is basically ready. The only remaining step is to pump the contents of drum #3 into a larger tank used to fill up the truck.

The final step is water separation. The tank used for filling up the truck has a filter on the hose to separate the water out as the fuel is pumped into the truck.

This process has been used by my friend for about 7 months. I think his truck is either a 2006 or 2007 F250.

So based on the process above, what is the "bad" part of what he is doing?