1 Normal spark plug 🔻 Light brown or gray color on the spark plug tip, indicating normal combustion and no problems. 2 High fuel consumption 🔻 Clear blackness on the spark plug tip due to a rich fuel mixture or clogged air filter. 3 Weak air/fuel mixture 🔻 The spark plug tip is light or white, which may indicate a lean fuel mixture or air leak. 4 Excessive amount of additives 🔻 Red or light brown deposits, often from poor fuel additives or anti-corrosion materials. 5 Bad valve stem seals 🔻 Oil on the spark plug tip due to leakage from the valve seals. 6 Damaged valve or broken piston ring 🔻 Wear or damage on the spark plug tip with abnormal deposits. 7 Prolonged engine operation with detonation or low octane fuel 🔻 Signs of irregular combustion or pre-ignition. 8 Oil burning 🔻 Thick oily deposits due to engine oil consumption or ring wear. Greetings to all.. 💐