If you search the MTX4, MTX4R, and probably MTX3 threads, you can easily find an answer to this. They will leak but you can do a couple things to slow it down. New gasket is good but you also need new o'rings. Also put some RTV on the gasket when installing it. Doesn't matter which kind, I think black RTV is considered all purpose. I usually used orange just because that's what I had. Depending on how much you run it, you'll have to pull it apart to fill it up occaisionally no matter what you do.