No...there is no 'nutrition' in used motor oil. It's petroleum. Fertilizers work by adding nitrogen and other nutrients to the soil. Besides, why on earth would you want to spread that on your lawn? Doing so causes it to leach into the ground, the water supply, and will probably kill whatever you might have growing.
Petroleum is toxic to plants, so keep it far away from any growing things. Used motor oil also picks up heavy metals from the engine, especially old engines, so it's even worse.
Should probably use 10 w 30 or 30 w.
regular 10w 30 motor oil
Yes, it is a premium oil that can be used in any internal combustion motor.
Yes, it sure will. Bar oil is not formulated for use in an internal combustion engine and will damage that engine.
regular 10w 30 motor oil
20-50 motor oil
No, you should not use bar and chain oil as a substitute for motor oil in a lawn mower. Bar and chain oil is specifically formulated for use in chainsaws and is designed to adhere to metal surfaces under high pressure and temperature, while motor oil is formulated to lubricate engines. Using the wrong type of oil can lead to improper lubrication, increased wear, and potential engine damage. Always refer to your lawn mower's manual for the recommended oil type.
If its got a oil plug its a 4 cycle, 5w-30 motor oil
I don't think you need to. There is no motor, so it doesn't need oil.
To lubricate the motor to prevent overheating and wear and tear on the engine
You will burn the motor up, which will be a very costly repair.
Usually no difference except that later model vehicles require a multi-viscosity oil (5w-30, 10w-30. etc) while the regular 30w is recommended for small engines such as a lawn mower.