How to Clean Your Car’s Underside to Keep It Running Right

Your car’s paint and bodywork get lots of looks and attention every day, but the underside can suffer from “out of sight, out of mind.” Mud, dirt, and grime can build up on your car’s suspension components and chassis. For many folks, winter means salt on the roads, which can cause corrosion if left to sit on your car’s undercarriage, and extreme crud buildup can even interfere with or damage critical suspension pieces. While you might not want to go to extremes to make your car’s underside show-car perfect, a basic cleaning every three months makes a big difference—both for appearance and your car’s reliability and longevity.

Prepping Your Car, And Yourself

Before you start, remember that you’re cleaning the part of your car that comes face-to-face with potholes, mud puddles, and dirt roads. Oil, grit, and grease will drip off as you work, so do this job in a place where you don’t mind getting dirty. As always, wear safety glasses and nitrile gloves.

Most major chassis components can be reached without lifting the car. If you want to raise your vehicle for better access, use jack stands or ramps—never work underneath a car resting on a jack. Wait an hour after driving to allow the exhaust system and other hot components to cool down and work in a shady spot.

Before you start cleaning, inspect the undercarriage. Grease streaks or oil deposits might indicate a leaking shock absorber or an oil leak from the engine or transmission. If you see white water spots under the car’s front end, it might indicate a leaking coolant hose. It’s better to fix a minor problem before it becomes a major repair or leaves you stranded on the side of the road.

Steps to Achieve a Clean Undercarriage

• Spray down the underside of your car with a light stream of water from a hose. Avoid using high pressure or a power washer, which can damage sensitive electrical components.
• Next, use an all-purpose cleaner and a long-handled brush to scrub away any heavy deposits of dirt or grease.
• Rinse again with a gentle spray of water. Remove any stubborn clumps with a rag.
• Now that the car’s undercarriage is clean, you can apply detail spray or a silicone-based finish like Chemical Guys Bare Bones. Spray on and wipe off with a clean cloth. This isn’t just for a car-show shine: Protective coatings can repel dirt and grime, keeping your car looking factory-fresh and making the next scrub-down easier.
• Between cleanings, occasionally glance at your car’s chassis, checking for signs of leaks or other problems. As you get to know your car’s underside, you’ll be better able to detect anything amiss.
• While most folks pay attention to washing their car and keeping a fresh coat of wax, regularly cleaning your car’s underside will help keep it running safely for a long time.