Some of them say that it adds to the lubricity of Diesel, some of them have noticed increased smoothness, some of them have noticed increased mileage. Truckers and bus drivers follow this regularly. I don't know how true is this, but it might surely add more oily residue to the fuel lines, diesel filter and shall ruin the cat-con as it might not be designed to take the uburnt HC from oil.
With the modern CRDI technology, which is much sensitive to even slight impurities, I dare not try this. BTW, mixing weird things has become a trend, who knows after sometime someone says drinking diesel cleans the stomach.
P.S: have you found the solution for the wet mat problem? I am really pissed-off at it, adding to that the accident took out the front left plastic wheel arch assembly.
@mastersquall: You lazy guy!