start it with a blend, say 20% oil and 80% diesel

and see how it is from there

increase the dosing until you find the performance drops or the smell becomes too much.

be prepared to change the filters alot more often, and remember used vegetable oil is better than new

oh....and pay the duty on it (about 35p a litre), all the forms are available from

www.hmrc.org.uk

good luck