I like to use Permatex type 3 aviation gasket glue. It's impervious to just about everything-gas, oil, heat, water. Someone on here years ago recommended it for intake manifolds. I was always chasing vacuum leaks using only rtv silicon. Same with annoying oil leaks. Brushes on nice and smooth; gives you better control on gasket glue oozing out and contaminating oil pick-up.