thinking of running my 1994 1.7 td astra van on a mix of cooking oil and diesel mix probably 25% cooking oil and 75% diesel to start with to see how it goes . has any one got any advice or tips having done this . do i need to thin the cooking oil with something ? i seem to remember someone saying you need to mix it with a small amount of white sprit or something any other advice would be helpful , i know i will need to declare this for tax purposes many thanks Paul.