My Ford dealer has just quoted me £170 for a service on my 06, 27000 mile tdci Mondeo. As I have nearly 2 years of warranty left I'll go with it. He asked if I wanted the engine flush treatment at £39. He said that this would help clean the residues out of the engine as well as cleaning the injectors. Is the treatment worth the extra or would I be better off spending my hard-earned on quality fuels like BP Ultimate diesel which I frequently buy anyway. All responses greatly appreciated.