My sister, honestly, :-), has just put £15 (21 l) worth of unleaded into my astra diesel estate. The tank holds 50 l, do i need to syphon some out before i fill it up, or will it run. The car has not been started yet. If i do need to syphon it, any suggestions, as i can't get a hose down to the petrol tank. Any suggestions greatly accepted, as I am about to strangle my sister!!!! Cheers Dave