Generally, unopened motorcycle engine oil can be stored for about 5 years, while opened but unused oil can last for about 6 months. Regardless of the type of oil, this duration is sufficient to support the motorcycle until its next maintenance. The reasons for oil contamination and deterioration: Engine oil (full synthetic, semi-synthetic, mineral oil) typically has a shelf life of 4-5 years. The contamination and deterioration of stored oil are mainly caused by its exposure to moisture, oxygen, and impurities in the air. Therefore, opened oil must be sealed for storage. Methods for storing opened engine oil: Seal immediately after opening. After completing maintenance at the repair shop, the oil bottle cap should be tightened immediately. It's important to note that since the original tin foil seal has been damaged, the remaining cap gasket provides limited isolation. At this point, a clean plastic film can be used to cover the bottle mouth. To avoid tearing, it's best to fold the film several times before covering, then screw on the bottle cap for a better sealing effect. If possible, wax can also be dripped around the bottle cap for sealing. After sealing the oil bottle, it should be stored in a dry and cool place, ensuring it is not exposed to sunlight to prevent oxidation of the oil inside. When retrieving long-stored oil for the next maintenance, do not pour it completely into the engine. Retain a small portion, as generally, there may be trace amounts of moisture at the bottom of the bottle after prolonged storage. Adding this to the engine could affect its performance or even cause adverse effects.
