To change the motor oil of a Royal Enfield Classic 350, first park the motorcycle on a stable surface and make sure it is well balanced, preferably with the center stand. Start the engine for a few minutes, just to slightly warm up the oil, so that it can flow more easily. After turning off the engine, place a container for collecting the oil under the drain plug, located under the engine. Gently unscrew the plug, allowing the used oil to flow into the container, allowing all the liquid to drain. When the flow is finished, clean the area around the plug and screw it back in carefully, making sure it is tightly closed to prevent leaks in the future. Now, remove the top cap of the oil tank and start pouring in the new oil suitable for the Classic 350 specifications. Proceed slowly and check the oil level during filling to avoid exceeding the recommended limit. Once the correct level is reached, screw the cap back on and start the engine for a couple of minutes to allow the oil to circulate. After turning it off, recheck the level and adjust slightly if necessary.