It looks like you're mentioning a specific brand and type of engine oil, which is Balwan CNG Oil 20W50 API SL. It appears to be designed for use in engines that run on both petrol (gasoline) and compressed natural gas (CNG). The API SL specification indicates that the oil meets the performance requirements set by the American Petroleum Institute for gasoline engines.
Using the appropriate engine oil is crucial for maintaining the performance and longevity of your vehicle's engine. When choosing an engine oil, it's important to consider the manufacturer's recommendations, the specific requirements of your vehicle, and the type of fuel it uses (in this case, both petrol and CNG).
It's advisable to follow your vehicle manufacturer's guidelines and recommendations when selecting engine oil to ensure proper lubrication and protection for your engine. If you have any doubts or questions about which engine oil to use, you may want to consult your vehicle's owner's manual or reach out to a qualified mechanic for advice.