If you follow Scotty Kilmer, the no-nonsense mechanic with decades of experience, you’ve likely seen him condition suspension parts on YouTube. He’s known for his quick, practical advice on keeping your car running smoothly without breaking the bank. When it comes to suspension, Kilmer emphasizes that many components—especially rubber bushings, ball joints, and sway bar links—can be revived rather than replaced. Conditioning suspension parts means using specific treatments to soften dried-out rubber, reduce squeaks, and restore flexibility. This article breaks down what Scotty Kilmer does in his videos, why it works, and how you can apply these methods to your own vehicle.
What Does “Conditioning Suspension Parts” Mean?
Conditioning suspension parts refers to applying products that penetrate, swell, and protect rubber and polyurethane components. Over time, heat, road grime, and age cause rubber to harden and crack. Hard bushings lead to a harsh ride, clunking noises, and poor handling. Kilmer’s approach is to rejuvenate these parts by using chemicals that restore pliability. This is not a permanent fix but can significantly extend service life, especially on older cars where replacements are costly or hard to find.
Why Scotty Kilmer Recommends Conditioning
Kilmer is a proponent of “fix it if it’s not broken.” He argues that many suspension parts are replaced prematurely. In his videos, he shows that after conditioning, bushings and joints often return to near-original condition, eliminating noise and restoring ride quality. He typically targets front lower control arm bushings, rear trailing arm bushings, and stabilizer bar links. The key is using the right product and technique.
The Step-by-Step Process Scotty Kilmer Uses
Here is the general process Kilmer demonstrates on his channel. It requires a few tools and specific chemicals.
1. Identify the Problematic Parts
First, locate the source of clunks or squeaks. With the car on jack stands, pry on control arms and sway bars. Hard, shiny rubber with cracks is a candidate for conditioning. Kilmer often uses a screwdriver to check for movement and listen for noise.
2. Clean the Rubber Thoroughly
Dirt and grease prevent conditioners from penetrating. Use a degreaser or brake cleaner (non-chlorinated) and a stiff brush. Wipe dry. In some videos, Kilmer uses a simple soap-and-water wash followed by compressed air.
3. Apply the Conditioner
Kilmer typically uses a product like “Kroil” or a specialized rubber conditioner. He sprays or brushes it onto the bushing, ensuring it seeps into the cracks. For bushings in metal sleeves, he may inject the conditioner using a small syringe. He emphasizes letting it soak for at least 15–30 minutes, sometimes overnight.
4. Work the Suspension
After applying, he moves the suspension arms through their range of motion. This helps distribute the conditioner into the rubber. He may bounce the car or use a pry bar to flex the bushing. In some clips, he applies the conditioner while the car is on the ground to load the suspension.
5. Repeat if Necessary
For severely hardened parts, a single application may not be enough. Kilmer recommends reapplying after a few days. The rubber gradually softens as the conditioner soaks in. If noise persists after two treatments, replacement may be needed.
Products Scotty Kilmer Mentions (Without Brand Endorsement)
While Kilmer doesn’t stick to one brand, he often recommends:
- Rubber conditioner: Products designed for weatherstripping or suspension bushings. Look for ones that say “rejuvenator” or “swelling agent.” Avoid petroleum-based greases that attack rubber.
- Penetrating oil: Sometimes he uses a light oil like WD-40 Specialist Rubber Lubricant or a silicone-based spray. These soften rubber without causing swelling.
- Hydraulic jack oil: In some older videos, he uses cheap ATF (automatic transmission fluid) as a low-cost conditioner. It can soften rubber but may attract dirt.
Important: Always test on a small area first. Some chemicals can cause rubber to swell excessively or degrade. Stick to products labeled safe for rubber.
When Conditioning Works vs. When to Replace
Conditioning is best for:
- Rubber that is hard but not crumbling.
- Parts with surface cracks less than 1/8" deep.
- Squeaks that go away temporarily after rain or car wash (moisture softens rubber).
- Budget-limited situations or when OEM parts are backordered.
Do not condition if:
- Rubber is torn, missing chunks, or crumbling.
- Metal sleeves are rusted through.
- Ball joints have excessive play (conditioning won’t fix metal wear).
- The part is safety-critical (e.g., steering rack bushings with slop).
Practical Tips from Scotty Kilmer’s Videos
- Use jack stands: Always work safely. Conditioners are slippery on the floor.
- Don’t overcondition: One thin coat is better than a heavy gob. Excess can attract grit.
- Combine with silicone grease: After conditioning, apply silicone grease to exposed surfaces to keep rubber supple longer.
- Wait before judging: Give the conditioner at least 48 hours to fully penetrate. Drive gently during that time.
- Check after rain: If noise returns after a rain, that part is a candidate for repeat conditioning.
Common Mistakes to Avoid
- Using WD-40 Original: It can clean but leaves a residue that may degrade rubber over time. Use a dedicated rubber lubricant.
- Applying to hot parts: Let the suspension cool down. Heat speeds evaporation and reduces absorption.
- Neglecting alignment: After conditioning, especially if you replaced any parts, have the alignment checked. Soft bushings can change camber.
- Skipping the cleaning step: Dirt acts as a barrier. Without cleaning, the conditioner can’t reach the rubber.
Final Recommendation
Scotty Kilmer’s method of conditioning suspension parts on YouTube offers a cheap, temporary fix for common suspension noises. It works best on rubber bushings that are simply hardened with age. If you’re on a tight budget or want to buy time before a full replacement, follow the steps: clean, apply a quality rubber conditioner, work the suspension, and repeat if needed. For most daily drivers, conditioning can silence squeaks for several months. However, if the part is already worn beyond surface cracks, replacement is the only safe route. Combine conditioning with regular inspection to catch real issues early. Your car will ride quieter, and your wallet will thank you.