My friend bought a vehicle from an auction and they had written some numbers on the windscreen with some sort of marker pen. Although they have been wiped off, when it rains or you use the windscreen wipers the outline of the numbers is still visible despite being cleaned with various cleaning agents. Can anyone suggest anything that will remove them entirely?
White spirit (the stuff that you clean paint brushes with) should do the job. (If you've not already got some, a bottle will cost very little in Wilkinsons or possibly Tesco Extra).
However, please take care to keep white spirit away from the car's paintwork. Also, don't let it come into contact with the rubber seal around the windscreen. (Just put a small amount of white spirit on a piece of kitchen towel and wipe it over the glass).
Meths should also work, and won't be dangerous to the paintwork.
While white spirit, used as instructed will cause no problem paint-wise, it will itself leave a film on the window which could cause a problem visually (I'm not sure, but I know the residue stops adhesives sticking)