I ran the cheapest 30 w oil I could find for more than 50,000 miles in a 1978 puch moped and it never broke down for any reason not evan 1 time.
What kind of engine? lawnmower, car.
If it is a 2 stroke use 80/90. Weight gear oil. If its 4 stroke run what specified on the engine
The best way to know if an engine is 2-stroke or 4-stroke, is to look for an oil spout. If the engine has an oil spout where oil has to be poured into, it is a 4-stroke. If the engine has no oil spout and the oil has to be added to the fuel, then it is a 2-stroke.
It is possible to use 4-stroke oil in a 2-stroke engine in an emergency situation. You should not use this oil in the long term as it will damage the engine.
If it is a 2-stroke engine, 2-cycle engine oil is added to the gasoline. If the engine is 4-stroke, regular 30W motor oil is used. To tell if your engine is 2-stroke or 4-stroke, look for a spout where oil is poured into the engine. If there is no spout, then the engine is 2-stroke and 2-cycle oil must be added to the gasoline.
There is no oil to change in a two stroke engine. The lubricant is the oil that is mixed with the gas.
Drain it out and replace with proper oil
It depends if it is a 2 stroke or a 4 stroke. A 2 stroke engine, you mix the gas and oil. A 4 stroke engine, there are separate tanks for the oil and gas.
No - it is formulated very differently. The crankcase of a four stroke engine needs conventional engine oil. DO NOT use two stroke oil in the crankcase.
No you can not.
If it is a 2-stroke engine, the oil/gas mixture has too much oil. If it is a 4-stroke engine, the oil sump is overfull.
You can use four stroke oil for a (very) limited period in a two stroke engine in an emergency. However it is not formulated for two stroke engines and is not recommended.