Vehicle will operate as if under heavy load.
It might damage the engine because it might be to viscous. You need to check the manual for compatibility. Some engines allow refill with more viscous oil.
the cake would be nasty and dry
there would be no oil and they would fail and lose money.
Generally you can mix the oils without a problem, check the oil manufacters label for any warnings.
oil would fill the lands
Water and oil are not miscible.
A bit more information would be useful, like how many miles are on the vehicle. If it isn't a high mileage vehicle, it might be a bad oil pressure sensor.
everyone will die
Cooking oil is a generic term for any oil you cook with - olive oil, palm oil, soya oil, peanut oil, ... It is for cooking, not for other buisness.
I would use the basic oil; However if your vehicle has high mileages, I would recommend synthetic oil by Mobil 1.
If there was a oil spill the entire ocean ecosystem would be at risk.