Blue spots on the guide bar indicate which issue?

• A. Chain too tight
• B. Not enough oil
• C. Both
• D. No wear

Answer: (C)

Blue spots on the guide bar show heat damage from friction between the chain and the bar. That friction comes from not enough lubrication or from the chain being too tight, both of which increase drag and generate heat. Because either condition can produce that discoloration, blue spots point to lubrication and tension issues rather than normal wear or other problems. So if you see blue spots, check the bar oil level and adjust the chain tension as needed, while also inspecting for any other bar or chain damage.