How to prevent car rust in Hong Kong's humid environment
🚗 Editor’s thoughts: Why is Hong Kong particularly prone to rust?
As a car owner in Hong Kong, I can say with certainty: rust is the biggest enemy of Hong Kong cars!
There are several reasons:
- Humidity is high year-round : Hong Kong's average relative humidity is above 75% year-round, and even exceeds 90% during the rainy season.
- Coastal salt erosion : Whether you live along the coast of Hong Kong Island, Tsuen Wan offshore terminal, Tuen Mun or Tseung Kwan O, the salt mist blown by the sea breeze will adhere to the surface of the car, and the salt will accelerate metal oxidation.
- Heavy rain + temperature difference : When rainwater seeps into small cracks, if it is not dried in time, long-term water accumulation will trigger "chronic rust mode".
- Urban environmental pollution : Acid rain mixed with dust can also corrode car paint and chassis.
🔍 Common Locations of Rust (Hong Kong Version)
In the Hong Kong environment, special care should be taken in the following locations:
- Chassis (exhaust pipe, suspension arm, chassis)
- Wheel arch inner wall (especially the front wheel, where mud and sand easily accumulate)
- The bottom of the door edge strip (rainwater seeps in and is difficult to dry)
- Trunk floor (leakage or water accumulation)
- Engine compartment metal screws and brackets
- Paint areas with stone marks (especially high-speed flying stones)
🛡 Hong Kong's humid environment rust prevention guide
1. Wash your car regularly and dry it thoroughly
- Important : Don't assume rain equals a free car wash! Rainwater contains impurities and salt, which can cause rust to form more quickly.
- Recommendation: Wash your car every 1-2 weeks. For cars near the sea, it is even recommended to wash it once a week.
- After washing the car, try to dry it naturally in a cool and ventilated place or use a fan to dry it to avoid water droplets staying for a long time.
2. Waxing, glazing, and protective coating
- In addition to making the car shiny, waxing can also form a protective layer between the metal and the air, reducing oxidation.
- In humid areas of Hong Kong, highly hydrophobic coating/quartz coating can be selected → rain and dust are not easy to adhere.
- Re-wax every 3 months, or do professional coating maintenance every six months.
3. Chassis anti-rust spray
- It is common to see serious rust on the chassis of old cars during vehicle inspections in Hong Kong. Anti-rust spraying in advance can extend the life of the car.
- It is recommended to check the chassis condition once a year, especially around the rainy season.
- Anti-rust oil or glue spray can isolate moisture and salt.
4. Avoid parking on wet ground or near the sea for a long time
- Parking in an open-air parking lot near the sea for a long time → Salt spray will double the erosion.
- When parking in a basement, pay attention to ventilation and avoid parking in humid corners for a long time.
- If you really have to park outdoors, you can consider a car cover (choose a breathable and waterproof material).
5. Rainy season protection
- Check the chassis and wheel arches immediately after typhoon season, as heavy rain can push mud and salt water into metal crevices.
- After a rain, do not allow mud and sand to stick to the metal surface for a long time. The sooner you clean it up, the better.
6. Detailed location maintenance
- Door edges, fuel tank cap, and trunk rubber edges → Open them regularly to clean water stains and dust.
- The screw positions can be lightly coated with anti-rust oil (do not spray it on rubber or wires).
- If there are scratches, repaint immediately or apply transparent film for protection.
7. Extra tips for electric vehicles
- Although the bottom of the electric vehicle is protected by a battery shell, the metal bracket will rust just like the suspension.
- Because of its heavy weight, the chassis will rust when it gets wet, which will have a greater impact on riding safety.
💡 My additional thoughts
The editor has maintained his car for many years and found that rust prevention is not a one-time job, but a long-term habit .
In Hong Kong’s hot, humid and salty environment, ignoring rust prevention is equivalent to making your car chronically “sick”.
If you only wash your car a few times a year and don't do any chassis maintenance, the bottom of your car will look like a "rust farm" in 5-8 years.
On the contrary, as long as you develop the habit of regular inspections, keeping it dry, and applying protective coatings, your car will still remain healthy 10 years later and its value will be highly retained.
🚗 Hong Kong Car Anti-Rust Annual Maintenance Schedule
| Time | Rust prevention key points | Recommended Action | Editor's Tips |
|---|---|---|---|
| January-February (late winter) | Check at the beginning of the year + clean the accumulated salt | - Thoroughly clean the chassis and wheel arches<br>- Check the anti-rust spraying condition of the previous year<br>- Re-wax or coat | Although there is less rain in winter, the humidity is still high. At the beginning of the new year, clean off old stains first to avoid accelerated oxidation with the moisture in spring. |
| March-April (wet spring) | Coping with the humidity during the "return of the south wind" season | - Add a dehumidifier or desiccant to the garage<br>- Check the bottom of the car weekly for water droplets or mud<br>- Clean the water in the door strips | During the return of the south wind, metal is particularly prone to "sweat", and moisture adheres to the bottom of the car faster than you think, so dehumidification is very important. |
| May-June (early summer + rainy season) | Prevent rainwater from adhering for a long time | - After washing the car, be sure to blow dry it or drive it to dry.<br>- Check the mud and sand in the wheel arches in particular.<br>- If the coating fades, it needs to be redone. | Rainwater during the rainy season is very acidic, so leaving your car wet for a long time is like inviting a rust party. |
| July-August (midsummer + typhoon season) | Heavy rain & sea breeze salt spray protection | - Wash the underbody immediately after a rainstorm<br>- Check the chassis anti-rust coating<br>- Inspect the exhaust pipe connection | Typhoon tides and salt spray will destroy the protective layer within 1 day, and "emergency cleaning" is required after the typhoon. |
| September-October (clear and crisp autumn weather) | Maintenance and repair period | - Carry out annual chassis anti-rust spray<br>- Apply anti-rust oil to screw positions<br>- Check for hidden injuries | The dry autumn is the best time to do chassis rust prevention, which facilitates the rapid curing of the coating. |
| November-December (early winter) | Prepare for rust prevention next year | - Wax or seal the glaze once<br>- Check all scratches and touch up the paint<br>- Dry the gaps between the doors and the trunk after washing the car | Winter maintenance is about getting your car through the wet spring, so don’t be lazy. |
🛠 Annual key reminder
- Chassis anti-rust spraying : at least once a year. If the vehicle is over 5 years old, it is recommended to check every six months.
- Coating/waxing : Coating should be done once every 6-12 months, while waxing should be done about once every 3 months.
- Treat scratches immediately : Any exposed metal surface will oxidize rapidly in the Hong Kong environment.
- Parking location : Try to park indoors and avoid long-term outdoor parking near the sea.
