A number plate has to be clearly readable in any weather. Motorway trips leave it covered in insects, autumn and spring cake it in mud, and winter coats it with salt and de-icing chemicals. An unreadable plate can lead to a fine, and enforcement cameras simply cannot read it.
Over time the metal plate starts to rust at the edges and around the fixings, especially where the paint or film is scratched. A little care a few times a season keeps it clean and slows corrosion.
What you will need
Important: Do not use abrasive pads, wire brushes or solvents: they damage the reflective surface and the characters. Keep the spray off brake discs, tyres and glass.
Step 1
Wash the car, or at least the bumpers
If you can, wash the whole car, paying attention to the bumpers and the area around the plates. Close the windows, wet the bodywork, go over it with a sponge and car shampoo, then rinse.
Dried insects on the bumper and plate surround soften easily: spray a little WD-40 Multi-Use, wait a minute, wipe, then finish the spot with shampoo.
Step 2
Wash the number plate
Gently go over the plate with a soapy sponge, including the raised characters and edges. In winter soak the plate with water first to dissolve salt and grit before rubbing, otherwise the grit will scratch the finish.
Rinse off the foam with clean water.
Step 3
Dry the plate
Check that no dirt is left and dry the plate thoroughly with a clean cloth. On embossed plates run the cloth along the characters and edges once more, where water tends to sit. If a mark remains, wash again.
Step 4
Protect it from rust
Spray WD-40 Multi-Use over the plate, fixing screws and any metal surround. It displaces moisture and protects metal against oxidation and corrosion. Leave it for 3-4 minutes, then wipe off the excess with a dry cloth so the surface does not attract dust.
A pocket-sized WD-40 100 ml is handy to keep in the glovebox for treating the plate and fixings after a winter wash.
Step 5
Check the plate lights
Switch on the side lights and check that both bulbs above the rear plate are working. If the light flickers or is dim, switch off the ignition, carefully remove the lens and spray WD-40 Specialist Contact Cleaner onto the holder and connector. It removes oxidation and dirt, dries quickly and leaves no residue. Refit the lens and test.
Tip: If the plate screws are seized, soak them with
WD-40 Multi-Use 10-15 minutes before undoing them, and give the threads a light spray when refitting: next time the plate will come off with no effort.
What next
Wash and treat the plates once a month, and in winter after every wash or trip on salted roads. The same product protects hinges, door locks and fixings under the body.
These uses come from the experience of WD-40 users in many countries. Always follow the instructions and warnings on the product label.
More guides in «How to use».