How to Clean a Car or Truck’s Undercarriage

Undercarriage cleaning isn’t just about keeping a vehicle spotless—it’s about protecting the parts most vulnerable to damage. Road salt, mud, grime, and oil can collect beneath the car or truck, silently accelerating rust and mechanical wear. As a detailer, knowing how to clean and dress the undercarriage safely sets your service apart and extends the life of your customers’ vehicles.

Whether you’re performing a full correction detail or a seasonal maintenance wash, underbody cleaning should never be overlooked.

Why Undercarriage Cleaning Matters

The undercarriage takes a beating from road debris, harsh weather, and corrosive elements like salt and magnesium chloride. Over time, this buildup can cause:

  • Rust on suspension components, subframes, and brake lines
  • Accelerated wear on bushings and underbody coatings
  • Staining and discoloration on visible frame rails and fender liners
  • Long-term damage that reduces resale value and performance

How Often Should You Wash Your Undercarriage?

While most drivers rarely think about the underside of their vehicle, it’s crucial to clean it on a regular schedule, especially in harsher climates or driving conditions. 

The most important time of the year to clean a car’s undercarriage is after each winter, especially if your vehicle drives on salted roads. The salt that helps us drive safely also has corrosive qualities that will lead to deterioration and rust if left untreated.

Here are some other recommended cleaning times:

Driving Condition
Recommended Frequency
Winter driving (road salt)
Every 2–3 weeks
Off-roading or mud exposure
After every trail or event
Urban commuting/daily driving
Once a month
Classic/show vehicles
Every oil change or seasonally

Regular underbody cleaning helps you avoid long-term corrosion while maintaining a vehicle’s safety and longevity.

How to Clean the Undercarriage

Cleaning the undercarriage is more than just rinsing off road grime. Follow these steps to get it done right:

  1. Raise the vehicle safely (if necessary)
    If you’re working on a car with low ground clearance, use ramps or a lift to safely raise the vehicle. Always set the parking brake and use wheel chocks or jack stands as appropriate. This gives you proper access to frame rails, suspension parts, and fender liners for a more thorough clean.
  1. Rinse thoroughly with pressure
    Attach an undercarriage attachment to your pressure washer gun and rinse from front to back. Focus on areas where grime collects: wheel wells, suspension components, and crossmembers.
  1. Apply degreaser
    Spray Citrus Degreaser or Special Force directly onto greasy or oily areas. These are especially effective around the axles, skid plates, and transmission tunnel.
  1. Agitate with a brush
    Use a long-handle or bendable detailing brush to scrub into tight spots. This step helps loosen stubborn grime before your final rinse.
  1. Final rinse
    Rinse away all degreaser and contaminants with clean water. Continue until no visible suds or dirt remain.
  1. Dry thoroughly
    Use compressed air or a blower to remove standing water from hard-to-reach areas like frame holes, brackets, or coil springs. This step prevents rust and streaking.
  1. Apply undercarriage dressing
    Spray a silicone protectant like our Super Blue directly onto clean plastic and coated metal surfaces. Use an applicator if needed for even coverage. Avoid brake and exhaust components. Let dry to a deep, factory-black finish.

Watch the above steps in action (Bottoms Up was a prior option, similar to Super Blue):

Undercarriage Cleaning: Cars vs. Trucks

Cleaning methods vary slightly depending on vehicle type:

  • Trucks & SUVs
    Higher ground clearance makes it easier to access components, but off-roaders often collect heavy mud and need more frequent cleaning. Use a wider spray fan and prioritize frame rails, axles, and control arms.
  • Cars & Lowered Vehicles
    Tighter spaces mean more risk of missed spots or splashback. Use a low-profile undercarriage sprayer and extra lighting to inspect areas like rocker panels, subframes, and fender liners.

Both benefit from a professional-grade undercarriage dressing like Super Blue to enhance appearance and protect components between details.

Knowing how to safely clean a vehicle’s undercarriage can separate your detailing business from the competition.