Both Motul 5100 10w40 (semi-synthetic with ester) and Shell Advance Ultra 10W40 (100% synthetic) are reputable motorcycle engine oils, and both can provide good performance and protection for your Yamaha XSR 155. However, the choice between the two ultimately depends on your specific requirements, budget, and the recommendations provided by the motorcycle manufacturer.
Here are some factors to consider:
Performance: Synthetic oils generally offer better performance and superior protection compared to semi-synthetic oils. Shell Advance Ultra 10W40 being a fully synthetic oil may have slightly better lubrication properties and can handle higher temperatures and extreme conditions more effectively. However, the difference in performance might not be noticeable in typical everyday riding situations.
Engine requirements: It's important to check the owner's manual or consult the manufacturer's recommendations to determine the recommended viscosity and type of oil for your Yamaha XSR 155. They usually provide specific guidelines for the appropriate oil to use, and it's advisable to follow their recommendations for optimal performance and warranty compliance.
Budget: Synthetic oils generally tend to be more expensive compared to semi-synthetic oils. If budget is a concern, the Motul 5100 10w40 (semi-synthetic) may be a more cost-effective option while still providing adequate protection for your motorcycle's engine.
Ester additive: The ester additive in the Motul 5100 10w40 can provide additional lubrication properties and protection. Ester-based oils are known for their high film strength, resistance to shearing, and enhanced engine cleanliness. This can be beneficial for maintaining engine health and longevity. However, it's important to note that the overall oil formulation and performance depend on various factors, not just the presence of ester additives.
Ultimately, both Motul 5100 10w40 and Shell Advance Ultra 10W40 are quality oils, and either choice should work well for your Yamaha XSR 155. It's advisable to consider the manufacturer's recommendations, your specific riding conditions, and your budget to make an informed decision. If you have any doubts or concerns, consulting a knowledgeable mechanic or contacting the motorcycle manufacturer's customer support can provide further guidance.