The real question is this: Is it really worth finding out the hard way for the sake of a paltry few dollars worth of fuel? At the very least, the two stroke oil could cause plug fouling and it will cause the exhaust to be smoky for a while. But contrary to another answer, it won't harm the catalytic converter unless you dump a lot more 2-T into the tank or add it regularly. The oil will be seen by the cat as unburnt hydrocarbons, and in excess they can cause the cat to overheat and then become damaged.

Car engines can safely burn 2-stroke mix when it's added in small amounts. Add it to a full tank in batches of just a quart at a time and you'll be fine. Just don't dump the whole container in at once.

I can't imagine the reason, but NEVER do that (unless your car has a 2-stroke engine, which I doubt) or you might seriously damage the converter and probably your on-biard diagnostics might come up with an alarm or two.

If you have a modern car that is equipped with a catalytic converter, then yes, you COULD harm your catalytic converter by dumping gas mixed with two-stroke oil into your tank. Find some other use for this gas & oil mixture.

nothing will happen you mite get the odd 2 stroke oil smell