Mr. Gasket RTV (room temperature vulcanizing) is a high quality silicone sealant that is for most automotive applications. We know that other brand silicone sealants come in bright blue, red, or other colors, but the small amount that shows between the castings and gaskets stands out and doesn't look very attractive. The Mr. Gasket grey RTV (room temperature vulcanizing) blends right in and isn't noticeable next to most cast iron or aluminum engine castings. This silicone sealant is for use in most applications and is resistant to oil, water, and coolant. 3 ounce tube.