Use a wrench to remove the channel bar from your vehicle. Pull the channel bar from your vehicle.
Measure out 1 tablespoon of regular salt into a cup.
Add a small squeeze of lime juice into the cup. Use a mixing stick to mix the combination into a paste.
Apply the paste to any rusted parts on the channel bar. Leave the paste on the rusted parts for about three hours.
Use a toothbrush to scrub the rust off the channel bar.
Spray the channel bar down with a garden hose to remove the paste. Use a rag to remove any exterior dirt.
Use an all-purpose cleaner to remove any stubborn dirt from the bar.