Drain valves are my friend. Of course the last batch were lighter and a silver color where the old ones were heavier brass, so maybe they won't be my friend after a few years.
I started using these close to 20 years ago and on all my buses for last 14... When I first saw them was worried they might get knocked open by road debris or ?,,Knock on wood haven't had that issue yet... they work great and I don't burn my hands,arms or anything with hot oil anymore..!