Rubber weatherstripping around doors, the boot, the bonnet, and windows keeps water, dust, and wind noise out of the cabin. Over time, UV exposure, heat, and ozone cause the rubber to harden, crack, and lose its elasticity. Regular conditioning with the right products extends weatherstrip life significantly and prevents leaks and wind noise. The job takes about 15 minutes and costs only a few dollars in product.
Why Weatherstripping Matters
Failed weatherstrips let water into the cabin (causing rust, mould, and electrical damage to wiring and modules under the carpet), let in wind noise on the highway (often the largest contributor to highway noise), allow dust and pollen to enter the cabin (a problem on outback roads in Australia), and let air conditioning escape, reducing efficiency and fuel economy. Rubber dries out fastest on vehicles parked outside in direct sun – an Australian reality for most drivers, especially in northern and inland regions.
Signs of Failing Weatherstripping
Visible cracks or splits in the rubber, especially in the corners where the strip bends. Hardness when pressed – good rubber compresses easily, dried-out rubber feels almost like plastic. Wind noise that has gradually got worse over the years. Water leaks into the door cavities, footwell, or boot after rain or car washes. Doors that no longer seal with a satisfying thunk and instead make a hollow sound when closing. Cabin pollen filter that clogs faster than expected.
Products to Use
Use a silicone-based rubber protectant or a dedicated weatherstrip conditioner like Gummi Pflege Stift, 303 Aerospace Protectant, or Mothers Back-to-Black trim restorer. Avoid petroleum-based products like Armor All on long-term weatherstrips – they look good initially but can degrade the rubber over time and attract dust. Glycerine-based products are also safe and inexpensive. Never use WD-40 as a rubber conditioner – it contains solvents that dry out rubber, the opposite of what you want.
Application Procedure
Clean the weatherstripping first with a mild soapy water solution and a soft cloth, then dry thoroughly. Built-up grime, polish residue, and dirt prevent the conditioner from properly absorbing into the rubber. Apply the conditioner to a clean microfibre cloth (not directly to the rubber – this gives more even coverage and prevents drips onto paint). Wipe along the length of each weatherstrip, working it into the folds and corners. Let it absorb for a few minutes, then wipe off any excess so it does not transfer to clothing or interior trim. Repeat every 3 to 6 months for best results.
Areas to Treat
All four door seals (both the door-mounted strips and the body-mounted strips). The boot lid weatherstrip. The bonnet seal at the firewall. Sunroof seals if fitted. Windscreen and rear window seals where accessible. Window channel rubbers (the felt-lined channels the windows slide through – silicone helps the windows move smoothly). Rear quarter window seals on coupes and wagons. Convertible top seals if you have a soft-top.
Preventing Frozen Doors
In cold climates, properly conditioned weatherstripping is much less likely to freeze to the door frame overnight. The silicone coating reduces water adhesion and stops the rubber from sticking. Less relevant in most of Australia, but worth noting if you travel to the Snowy Mountains or Tasmania in winter. The same conditioning also helps in extreme heat by preventing the rubber from softening and sticking.
When Weatherstripping Needs Replacement
Conditioning extends the life of weatherstripping but does not bring back rubber that has already cracked or shrunk. If you can see cracks, the strip is folding back on itself, or sections are missing, conditioning will not help and the strip needs replacing. Most weatherstrips clip into channels or attach with adhesive and are replaceable as a DIY job. Some models offer the strip in pre-cut lengths matched to the door; others sell it by the metre.
For specific weatherstrip replacement procedures and part numbers, MechanicMate offers PDF workshop manuals for over 960 models at mechanicmate.net/shop.
— MechanicMate . Questions or a second opinion? [email protected].