Yes. Oil is hard on Catalytic converter.
Yes possibly but i would look for smoke as well since oil will create smoke when burned. I would think that dirty fuel that clogs the filter, or water mixed with the gas might cause stalling and would also come from bad gas stations.
Destroy the engine.
Excuse me, but this is a stupid and bad idea.
Nitrogen mixed with normal air
drain tank and refill
Adding a small amount of mixed gas and oil, like used in a string trimmer, will not hurt a vehicle. The car might smoke slightly until the mix is burned through.
It can.
It should be fine. Might smoke a little.
Battery? / Alternator? It's bad gas?
It starts running bad and changing the fuel fixes it.
depend on what kind of car it is
Yes.