Using two different viscosity grade oils, such as 10W40 and 5W30, in a motorcycle instead of using a single grade as recommended by the manufacturers can have several consequences:
Lubrication Issues: Different viscosity grades have varying flow characteristics at different temperatures. Mixing two different viscosity oils can result in an unpredictable viscosity range, leading to inadequate lubrication or excessive wear in critical engine components. This can result in reduced engine performance and increased friction, potentially causing damage over time.
Engine Stress: Motorcycles are designed to operate with specific viscosity oils to ensure proper lubrication and cooling. Using two different viscosity oils can create inconsistencies in oil flow and pressure, potentially placing additional stress on engine parts. This can result in increased wear, reduced engine life, and decreased overall performance.
Oil Breakdown: Mixing different viscosity oils can alter the chemical composition and performance characteristics of the lubricant. The additives in each oil may not blend well, leading to oil degradation and reduced protection against heat, oxidation, and sludge formation. This can result in decreased oil life and potential engine damage.
Warranty Voidance: Manufacturers specify the recommended oil grades for their motorcycles based on extensive testing and engineering considerations. Deviating from their recommendations by using different viscosity oils can void the warranty coverage on the engine or other related components, leaving you responsible for any repair costs.
Temperature Sensitivity: Viscosity grades are chosen based on the expected temperature range in which the motorcycle will operate optimally. Mixing two different viscosity oils can affect the oil's ability to flow and provide adequate protection at specific temperature extremes, such as during cold starts or high-temperature conditions. This can lead to increased engine wear and potential performance issues.
It is crucial to follow the manufacturer's recommendations regarding oil viscosity grades to ensure optimal engine performance, longevity, and warranty coverage. If you have concerns or specific requirements, it is best to consult with the manufacturer or a qualified motorcycle mechanic to determine the appropriate oil grade for your motorcycle.