What is the black plastic on the car door frame?

[AnnieAnn]

Car door frame black plastic is called door seal strip. Introduction to door seal strip: The door seal strip is a product that seals the car door, making it harder to open, and serves functions such as shock absorption, waterproofing, sound insulation, heat insulation, dust prevention, and fixation. Functions of door seal strip: The door seal strip (auto-door-rubber-seal-strip) is mainly used for fixing the door, dust prevention, and sealing. It is mainly composed of materials with good elasticity, compression resistance, aging resistance, ozone resistance, and chemical resistance. It contains unique metal clamps and tongue buckles, making it sturdy and durable, and easy to install. It is mainly applied to car door frames, side windows, front and rear windshields, engine hoods, and trunk lids, serving functions such as waterproofing, dust prevention, sound insulation, temperature insulation, shock absorption, and decoration.

[Raquel]

The black plastic strip around the door frame is actually called the door seal, primarily designed to prevent rainwater and dust from entering the car. I always make sure to check for cracks when washing my car, as any cracks can lead to water leakage. It's mostly made of rubber or PVC, so it's important to avoid prolonged exposure to sunlight, as it can harden and crack with age. A good seal can also reduce wind noise. During my last maintenance visit, the technician recommended applying rubber protectant every quarter to extend its lifespan. Don't wait too long to replace it—my neighbor delayed it, and the interior door components ended up rusting. When choosing replacement parts, always opt for OEM or reputable brands to ensure proper fit and avoid air leaks.

[Jeffrey]

This is the door seal strip, designed in black for dirt resistance and durability. I've found it serves three key purposes: first, it prevents rainwater from flowing along the window into the door interior during rainy days; second, it keeps dust from entering when driving on dirt roads; third, it significantly reduces noise at high speeds. The material is typically rubber – avoid scraping it with hard objects in winter as it's prone to cracking in low temperatures. My experience suggests using a damp cloth to carefully clean the grooves of sand particles during seasonal changes each year, as accumulated debris accelerates aging. Once I saw a friend's seal strip deformed, resulting in improperly closed doors and squeaky noises, which was particularly troublesome to fix.

[DeOscar]

This is called the window seal strip, which seals the gap between the car window and the body. It is most vulnerable to deformation from tree branches or door pinching, and once damaged, it can easily cause water leakage. The material is mostly synthetic rubber, which becomes brittle after years of exposure to sunlight. Every time I wash the car, I lift it to clean the track area to prevent dust buildup and corrosion. If the strip becomes hard or cracked, it needs to be replaced immediately; otherwise, dust can enter the cabin and noise levels may increase. When replacing, pay attention to the thickness—too thin a strip won't provide good sealing.

[OCaroline]

The black plastic on the door frame is the sealing strip, a key component for waterproofing and dustproofing. I recommend paying attention to these points: First, avoid using a high-pressure water gun directly on the edges when washing the car, as it can deform the seal. Second, promptly remove accumulated snow in winter, as ice shards can cause the rubber to crack. Third, don't slam the car door too hard—I've seen cases where the lock tongue punctured the seal. When selecting replacement parts, check the surface texture; genuine parts usually have anti-slip fine lines. If you find cracks, apply some rubber softening paste as a temporary fix, but it will only last a month or so before needing replacement.

[VonGenevieve]

The black plastic ring is professionally called a door weatherstrip, made of rubber that expands and contracts with temperature. I've discovered it has a hidden function beyond waterproofing: guiding the window's movement trajectory when rolling up/down, protecting the glass edges from hitting the metal frame. Avoid exposing it to engine oil or chemical solvents as they cause corrosion and deformation. New cars don't require maintenance for the first three years, but regular inspections are needed afterward. Last time mine developed a split at the end - I temporarily fixed it with sealant, but full replacement is recommended to prevent water leakage into door circuits.