Chain cleaner is a powerful solvent spray designed to strip away old, contaminated grease, road tar, and dirt from drive chains before re-lubrication. Applying new lube over a dirty chain creates a grinding paste that accelerates wear. This cleaner dissolves the sludge so it can be wiped away or rinsed off with water. Like chain lube, it must be specifically formulated to be “O-ring safe,” meaning it won’t swell or crack the rubber seals inside the chain links, which would ruin the chain.