It will hydraulic lock. This means that it will appear and feel as if it has siezed up but in fact it probably hasn't. To correct the problem you must drain the excess oil. Start by disconnecting the spark plug wire so the mower can't accidentally start up. Under the mower where the blade is you should find a plug going into the bottom of the motor. Remove that plug and drain the oil. Reinstall the plug and check your oil. fill only to the line on the dipstick. Reinstall the spark plug wire and your mower should start normally.
If all oil the mower will not start. If only a little oil, the mower may start but run rough and smoke very much.
If the lawn mower is run without oil, the connecting rod bearing will heat and score, or even "weld" to the crankshaft, causing major damage.
Engine wear and damage can occur.
give up and hire a lawn service...
No for your lawn mower you will just need regular lawn mower oil.
Automotive oil is identical to lawn mower oil. They are both internal combustion engines. I would however recommend you use 100% Synthetic oil in that air cooled lawnmower engine.
approx 20oz
Drain out the excess. Too much oil will damage the engine.
600mls
You will do serious damage to any 4 engine that you overfill. Drain out the excess oil immediately.
You will burn the motor up, which will be a very costly repair.
Kawasaki 15 HP Ariens Lawn Mower takes 1.2 Litres of oil and maybe a little more when you change the oil filter