Bad things will happen. Mix oil is designed to burn with fuel so it will not lubricate the piston enough and you will sieze the engine.
to put the oil in the lawnmower's crankcase would be fine, so long as it is an appropriate viscosity.
You can cut down trees with your lawnmower. Warning: Do not actually try to cut down a tree with your lawnmower. More than likely, the gas in the chainsaw is mixed with 2-cycle oil. If your mower also has a 2-cycle engine, nothing will happen. If your mower has a 4-cycle engine, the engine will probably smoke (bluish in color) until the oil is burnt up during combustion. At worst, the oil in the 2-cycle oil/gas mixture will foul up the spark plug and you will probably have to clean it pretty often until the oil is burnt up.
SAE 10w30 weight synthetic oil.
0.6 litres
Drain the oil and gas out of the crankcase and put oil back it should be OK
You get engine damage from lack of lubrication
Drain the oil and catch it in a clean container if you intend on reusing the same oil . Then replace the plug and place the correct amount of oil in the motor.
The engine floods and you have to wait for the lawnmower to drain before you start it up again or it might start smoking.
Apparently you didn't crank it up. You are still here. Nothing except it may clean out some old dirty oil. Remove the gas and the oil and discard same. Refill the oil section and refill the gas tank. Don't do that again.
If you mean 4 cycle oil in a 2 cycle bike, the answer is no. Use only 2 cycle oil in a 2 cycle motorcycle.
Most small engines use 30 weight non-detergent type.
Yitou can. But its not recommended. It wont run right. Stick with the manufacturers recommended weight.