It is generally recommended to replace the engine oil in your motorcycle rather than adding to it or attempting to drain it completely. Regular oil changes are important for maintaining the performance and longevity of your engine. Over time, engine oil can become contaminated with dirt, debris, and combustion byproducts, which can affect its ability to lubricate the engine effectively.
When you change the engine oil, you also replace the oil filter, which helps remove contaminants from the oil. Simply adding new oil without draining the old oil or replacing the filter would not address these issues, and the new oil would mix with the old, potentially reducing its effectiveness.
To properly change the engine oil in your Classic 350 Bullet, follow the manufacturer's guidelines outlined in the owner's manual. This typically involves draining the old oil by removing the drain plug, replacing the oil filter, and then refilling the engine with the recommended amount and type of fresh oil. By performing regular oil changes, you help ensure the optimal performance and longevity of your motorcycle's engine.