RTV Gasket Maker Colors Explained: Black vs Blue vs Red vs Grey
October 24, 2026 · RPS Distributors
RTV (room temperature vulcanizing) silicone gasket makers can replace or support traditional gaskets on many engine parts. The color usually tells you what the product is designed for. Using the right one helps prevent leaks and comebacks.
What the colors usually mean
Colors and ratings can vary by brand and product, so always read the label. As a general guide:
| Color | Typically used for |
|---|---|
| Black | Oil-resistant jobs such as oil pans, valve covers and timing covers |
| Blue | Water pumps, thermostat housings and general-purpose sealing |
| Red / high temp | Parts that see higher heat, such as some exhaust-area and engine parts |
| Grey | High-torque, rigid-flange applications, often on import engines |
| Copper | Very high-heat applications |
| Clear | General sealing where a clear finish is wanted |
Check the temperature rating and the "sensor-safe" label. Most modern RTV products are safe for oxygen sensors, but confirm before use.
How to apply RTV the right way
- Clean both surfaces of old gasket, oil and dirt. Brake cleaner works well.
- Apply a thin, even bead — usually around 1/8 inch — and circle bolt holes.
- Assemble the parts while the RTV is still wet, following the label.
- Tighten bolts finger-tight first, then torque to spec after the time the label recommends.
- Allow full cure time before adding fluids or running the engine.
Common mistakes
- Using too much — extra RTV squeezes inside and can block oil passages.
- Skipping cleaning — RTV will not seal on oily surfaces.
- Not waiting for cure time before filling fluids.
Frequently asked questions
What is black RTV used for?
Black RTV is typically used for oil-resistant jobs such as oil pans, valve covers and timing covers. Colors vary by brand, so always read the label.
How thick should an RTV bead be?
Apply a thin, even bead, usually around 1/8 inch, and circle the bolt holes. Too much RTV can squeeze inside and block oil passages.
Is RTV safe for oxygen sensors?
Most modern RTV products are sensor-safe, but check the label to confirm before use.
Permatex products we carry
RPS Distributors stocks Permatex gasket makers, The Right Stuff, adhesives, threadlockers and sealants. Browse the Auto Accessories collection.
Request a wholesale quote or call 1-855-498-7509.