JB Weld, or, in my case, the two part small tubs if industrial DevCon plastic steel epoxy already on hand. It will repair holes in gas tanks, permanently if fuel is drained first into one of your large tubs, metal radiator tanks, oil pans, cracked engine block even, water pump block and pump housing, pump impellor if you happen to suck up a nasty that busts or cracks the impellor, it will rejoin the impellor parts until it can be replaced, etc, etc, etc. Be patient, let repair cure overnight, use a wee extra hardener. For so many metal repair possibilities its weight and storage room are minimal, and may make the difference of getting back out that isolated road without an expense return rescue trip or tow or just disrupting a whole prospector outing. A must with the tool collection.