Which grade of silicone sealant is used in high temperature applications?

• A. Blue
• B. Green
• C. Yellow
• D. Red

Answer: (D)

Silicone sealants are labeled by temperature rating, and the color code helps you pick the right one for the heat you’ll see. Red is the high-temperature grade, formulated to stay flexible and maintain a reliable seal under elevated engine and exhaust temperatures and through repeated heating and cooling. That makes it the best choice for hot areas such as exhaust connections, cylinder head covers, and other hot-end locations.

Blue is typically a general-purpose grade for normal engine temperatures, not intended for sustained high heat. The green and yellow variants serve other properties or brand-specific formulations and are not chosen for continuous high-temperature service. When in doubt, check the product’s specifications for maximum service temperature.