Rubber seals on doors, windows and the boot keep the cabin dry and quiet. Between winter frost and summer heat the rubber dulls, hardens and cracks, and in freezing weather it also sticks to the body: the door will not open or the seal tears.
Regular care takes a few minutes and adds years to the life of your seals. If the rubber is already torn or coming away, it is better to replace it, as covered in our separate guide.
What you will need
Important: Keep silicone off the windscreen, wiper blades and brake discs. Wipe off any overspray immediately and shield nearby glass with a piece of card.
Step 1
Inspect the seals
Open all the doors and the boot and lower the windows. Go round every seal looking for cracks, tears, lifted corners and worn spots. Small lifted sections can be glued with rubber adhesive; a badly damaged seal should be replaced.
Also check the drain holes at the bottom of the doors: if they are blocked, water sits there and the rubber deteriorates faster.
Step 2
Wash and dry the rubber
Wipe the seals with a sponge, warm water and car shampoo. Sand, salt and dirt act like an abrasive on rubber, so remove them before treatment.
Dry everything with microfibre and give it a few minutes for moisture to leave the folds of the profile.
Step 3
Apply silicone
Spray WD-40 Specialist Silicone onto the seal in a thin, even coat from about 15 to 20 cm, one section at a time. Near glass it is easier to spray onto a cloth and wipe it on.
Silicone is safe on rubber and plastic, repels water and dust, and restores suppleness and a fresh look.
Step 4
Let it soak in and spread it
Leave it for about a minute to soak in. Then go over it with a clean microfibre cloth to spread the silicone and remove the excess. The surface should look satin, not wet.
Close the doors once the treatment has dried.
Step 5
Prepare for frost
In autumn, before the first frosts, treat all door, boot and sunroof seals with silicone. The film stops water clinging to the rubber, so the doors will not freeze shut overnight.
If a door does freeze, do not yank the handle: press firmly on the door to break the ice and then open it gently.
Step 6
Do not forget hinges and locks
While the doors are open, treat hinges, check straps and lock cylinders with WD-40 Multi-Use. WD-40 Smart Straw makes it easy to spray into the lock through its straw. It displaces moisture so the lock will not freeze and the hinges will not squeak. Wipe off the excess.
Tip: Treat the seals not only before winter but also in spring after the salt season. In summer sun the rubber dries out just as much as in frost.
What next
Repeat every 2 to 3 months and always in autumn. If a seal is already torn or shrunken, see how to replace a window seal yourself. Keep WD-40 Specialist Silicone in the garage with your other seasonal care products.
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».