You can use any type of permatex and it will last for the summer. NO ONE WILL RE WELD THE TANK. only other option is to bore out the fitting and thread it and then use pipe dope on a fitting that matches the hole. My tanks had the fuel inlet fitting welded but the fuel pick ups were threaded. Just remember, dont grind ,saw, drill anything without proper venalation, the spark from the drill motor will set off the tanks. The tanks are alumninum so you wont get any sparks from a drill or saw, but the high rpm's of a grinder will.