How Would You Fix Small Hole in Oil Pan (a la mexicana)?

Here's the ultimate in cheap solutions, a bar of soap. I've used it many times to plug a hole or crack in fuel tanks and hydraulic tanks. Granted these vehicles were going to scrap or were in accidents. Petroleum won't disolve bar soap.

Just rub the soap on the crack or hole until filled with soap. It's a great way to get you home in an emergency, but you have to check it all the time.

If he must use silicone, use permatex Right Stuff. It's more impervious to petroleum products than plain old silicone.

Of course to proper way, as everyone has stated, is to weld or replace.