Hi sma65
I would have a look in the handbook before you try biodiesel, according to my handbook it's a complete no, no. That's on the 2007 model. Also watch what oil you use as well, I've now had it from various sources that the Kia diesels are quite sophisticated engines and the only oil to meet requirements is Castrol Magnetec Professional C3. Mine wanted barely a cupful in after 8,500 miles but I've had to bite the bullet and buy the above.
Tomo