Cut up an old inner tube and layer it. Use goop glue to the sides of the bag. Rubber and metal make a good bond with goop glue. I glued a metal rod to the aluminum head for a camera mount. Heat did not weaken the glue so I'll assume the hot oil bag would almost act the same as the the hot head. Racing wise, a few zip-ties holds up to this kind of punishment. That's about as fancy a battery hold down strap as it gets.