Years (if not decades) ago I would sometimes come across a stripped oil drain. I could go to the local auto parts store and buy something that looked like the nipple on a baby bottle (but much thicker) to jam into the drain hole. It came with a special tool to expand the end as you inserted it. It worked great and I drove many many miles with those things.
Does anyone know if they still exist and/or where I could get one? They were a lot easier (and cheaper) than a helicoil. I've spent a lot of time googling for it and can't find anything close.