If you put 2 cycle oil in a 4 cycle engine it could damage the engine because the 2 cycle engine oil is thinner than normal 4 cycle engine oil.
However if you've added a bit of 2 cycle engine oil to the regular oil then nothing will likely happen but you should still change the oil and replace it with regular 4 cycle engine oil.
The oil that is best for 2 stroke engines is echo 2 stroke engine oil and supertech 2 stroke engine oil.
I've used both supertech 2 stroke engine oil and echo 2 stroke engine oil and they both are good oils.
The supertech 2 stroke engine oil is what I mostly use and never had any issues with it and it's cheaper than echo and some other brands.
Not all 2 cycle engine oils are the same.
Some brands of 2 cycle engine oil are formulated differently for different 2 cycle engines.
Two-Stroke oils come in 3 different types.
Natural mineral oil, Semi-Synthetic and Completely Synthetic oils.
While synthetic oils are considered to be the best out of the lot, their cost makes it not the usual choice for old bikes or for gardening equipment.
Briggs and Stratton 2 cycle oil is synthetic.
Small engine oil and 2 cycle oil are not the same as they have a different formula and different thickness to them.
Two-stroke oil (also referred to as two-cycle oil, 2-cycle oil, 2T oil, or 2-stroke oil) is a special type of motor oil intended for use in crankcase compression two-stroke engines (typical of small gasoline-powered engines).
SAE 30 oil is okay for the 2 cycle engine although it's not the same exact thing.
You can use SAE 30 4 stroke engine oil in a 2 cycle engine and it will be fine.
You cannot and should not use regular oil in a 2 cycle engine.
Using regular oil in a 2 cycle engine could cause engine damage and may even cause the engine to not start.
You want to use 2 cycle engine oil that is formulated properly for the 2 cycle engine.
The type of oil that a 2 cycle engine takes is 2 cycle engine oil or 2 stroke engine oil which is commonly sold in small bottles.
Although you can buy quarts and even gallons of 2 cycle engine oil.
The 2 stroke engine oil is specially formulated for lubricating 2 stroke engines and is just the right thickness.
Running the wrong engine oil in a 2 stroke engine can damage it or cause the engine to not run at all.
A 2 cycle engine is lubricated through the carburetor and gasoline as it gets combusted.
Unlike a 4 cycle engine that has an oil pan and the oil gets thrown up unto the pistons etc to lubricate it the oil for the 2 cycle engine is mixed in with the gasoline and as the gasoline is burned the engine gets lubricated through the mix of the engine oil.
This is why it's important to mix the oil and gas properly as too little oil can cause the engine to not get enough lubrication.
Two-stroke engines use their crankcase to pressurize the air-fuel mixture before transfer to the cylinder.
Unlike four-stroke engines, they cannot be lubricated by oil contained in the crankcase and sump: lubricating oil would be swept up and burnt with the fuel.
A 2 stroke pulls air fuel down into the crankcase and pressurizes transfer ports.
That circulation of air /fuel mixture through the crankcase is all it takes to lube the bottom end.
it provides a light coating of oil.
A two stroke engine has neither and oil sump or pump.
The oil is added to the fuel and flows through the crankcase lubricating the moving parts before being burned in the combustion chamber.