start off slowly matey,whacking a full tank of oil or bidiesel can cause problems(blocked fuel filter and fuel lines),i have been advised to go 10% biodiesel first then 20 ,40,60 up to full on 100%.once the car is running fine like this,then off you go,you can use a cocktail of oil/biodiesel and normal pump stuff if you must.
edit :depends on what engine you have also.older non pd engines are fine.pd engines its a very BIG no no
Haha you're well and truly converted now aren't you