Sealants
In my yoof it was red Hermetite & knackered faces & gaskets & ,surprise,surprise ,they leaked. Then instant gasket,effective but dangerous, Blue hylomar, effective on good gaskets/joints but too expensive. Quite a few others but the late John King got me back using red Hermetite. Cheap,effective,easy to get rid off. Follow the instructions & let it become tacky before bolting up. Dell Boy.