Using a clay bar on every surface of your vehicle can significantly enhance its cleanliness and smoothness, but it's important to understand where and how to use it effectively. Here’s a general guide based on the practices shared in communities like AutoDetailing:

Surfaces Where You Can Use a Clay Bar:

1. Painted Surfaces

• Primary Use: A clay bar is most commonly used on the car’s paint to remove contaminants such as tar, tree sap, road grime, and industrial fallout.
• Result: It leaves the paint smooth and ready for polishing or waxing.
• Lubricant: Always use a clay lubricant or detailing spray to prevent scratching the paint.

2. Glass (Windshield, Windows, Mirrors)

• Purpose: Claying glass helps remove stubborn water spots, sap, and other contaminants that normal cleaning may miss.
• Result: Leaves the glass ultra-smooth, improving visibility and making future cleanings easier.
• Lubricant: Use the same clay lubricant or detailing spray as you would for paint.

3. Chrome and Metal Trim

• Purpose: A clay bar works well on chrome, aluminum, and other metal surfaces to remove oxidation, road grime, and stuck-on debris.
• Result: Restores the shine to metal surfaces and helps prepare for polishing.
• Lubricant: Use clay lubricant or a spray wax as a lubricant.

4. Plastic and Rubber Trim

• Careful Application: While you can use a clay bar on some plastic trim pieces, it’s generally not necessary unless those surfaces are especially contaminated. Use caution to avoid scratching textured plastics.
• Result: Can smooth out lightly contaminated plastic surfaces, but polishing may be required afterward.
• Lubricant: Use clay lubricant and light pressure to avoid damaging the surface.

5. Headlights and Taillights

• Purpose: Claying headlights and taillights removes contaminants like bugs, tar, and oxidation that regular cleaning may not tackle.
• Result: Restores clarity to plastic or glass lenses, especially before applying a headlight restoration kit.
• Lubricant: Use plenty of clay lubricant to avoid scratching these delicate surfaces.

Surfaces to Avoid:

1. Matte or Satin Paint

• Avoid Claying: Matte or satin finishes should not be clayed, as the clay bar can alter the finish, making it shiny in spots.
• Alternative: Use products specifically designed for matte finishes.

2. Decals or Vinyl Wraps

• Exercise Caution: While some people use a clay bar on vinyl wraps or decals, it’s risky as it can lift or damage the edges. It's better to clean these surfaces using gentler methods like a wash mitt or detailing spray.

Tips from r/AutoDetailing Community:

• Always Lubricate: This is the most emphasized point. Use a dedicated clay lubricant, detailing spray, or diluted car wash soap and water to ensure the clay bar glides over the surface without causing scratches.
• Use Light Pressure: Don’t press too hard with the clay bar. Let the clay do the work by lightly moving it across the lubricated surface.
• Check for Contaminants: As you clay, feel the surface with your hand after each pass. The surface should feel smooth; if you still feel roughness, reapply the clay bar.
• Inspect and Fold the Clay: Keep checking the clay bar for dirt and contaminants. Fold it regularly to expose a clean section. If it gets too dirty, replace it.
• Post-Clay Waxing or Sealing: After claying, the surface will be free of contaminants but also unprotected. Apply a coat of wax, sealant, or ceramic coating to protect the surface and enhance shine.
• Be Careful with Soft Paint: Some vehicles have very soft paint that can scratch easily. If you're working on a car with a delicate clear coat, take extra care and use a fine-grade clay bar.

Conclusion:

Using a clay bar on every surface can greatly improve the overall look and feel of your vehicle, making it smoother and cleaner. Just be mindful of which surfaces are safe to clay and always use proper lubrication. Many auto enthusiasts on AutoDetailing recommend claying at least a couple of times a year to maintain your car’s exterior, especially before polishing or waxing.