the escort tdi is the same as focus near as dam it, try three litres to start . If it does not like it dilute with more diesel . My tank is always full i do about 300 ish miles aweek , i put my rape seed oil in then top up with diesel and thats it . my millers additive is about 7 quid and treats 500 litres of fuel . try the web www. vegetableoildiesel.co.uk or just type biofuel in . It is wierd putting food in your car but it works .And if it takes the edge of high fuel prices do it