Dexos Approved Oil: Why High-Mileage Oil Falls Short

Essential Information

Can I use high mileage oil in a vehicle that requires Dexos-approved oil.
No, it is not recommended to use high mileage oil in vehicles that require Dexos-approved oil.
High mileage oils have a different viscosity and additive package that may interfere with the performance of Dexos-approved oils.

Dexos is a performance specification developed by General Motors (GM) for engine oils designed to meet the specific requirements of GM vehicles. High mileage oils, on the other hand, are formulated for vehicles with higher mileage and address the unique challenges they face. So, why is it that high mileage oil is not Dexos approved? This blog post delves into the technicalities behind this decision, shedding light on the nuances of engine oil formulations.

Understanding the Dexos Standard

Dexos certification ensures that an engine oil meets stringent performance criteria, including wear protection, oxidation resistance, and fuel economy. It is a rigorous standard that requires extensive testing and validation. To obtain Dexos approval, an oil must pass a series of tests that simulate real-world driving conditions.

Why High Mileage Oils Differ

High mileage oils are designed to address the specific needs of vehicles with higher mileage. These vehicles may have accumulated wear and tear over time, leading to increased oil consumption and potential leaks. High mileage oils typically contain:

Higher Viscosity: To compensate for increased wear, high mileage oils have a higher viscosity, which helps maintain oil pressure and reduce leaks.
Additives for Seal Conditioning: These additives help rejuvenate and condition seals, reducing oil leaks.
Anti-Wear Additives: High mileage oils contain enhanced levels of anti-wear additives to protect against further wear and tear.

Why Dexos Certification Excludes High Mileage Oils

Despite their specialized formulation, high mileage oils are not Dexos approved due to the following reasons:

Viscosity Range: Dexos certification requires oils to meet specific viscosity ranges. High mileage oils, with their higher viscosity, fall outside these ranges.
Additive Package: The additive package in high mileage oils differs from that required for Dexos certification. The additional seal conditioning and anti-wear additives may interfere with the performance of Dexos-approved oils.
Testing Requirements: High mileage oils have not undergone the rigorous testing required for Dexos approval. This testing ensures that oils meet GM’s specific performance requirements.

Implications for Vehicle Owners

While high mileage oils are not Dexos approved, they are still suitable for vehicles with higher mileage. These oils provide specialized protection against wear and tear, reduce oil consumption, and help maintain engine performance. However, it is important to consult your vehicle’s owner’s manual for the recommended oil specification.

Choosing the Right Oil for Your Vehicle

Selecting the correct engine oil is crucial for maintaining the health of your vehicle’s engine. Here are some guidelines:

Follow Manufacturer’s Recommendations: Always refer to your vehicle’s owner’s manual for the specified oil type and viscosity.
Consider Vehicle Age and Mileage: If your vehicle has high mileage, consider using a high mileage oil.
Consult a Mechanic: If you’re unsure about the best oil for your vehicle, consult a qualified mechanic for professional advice.

Alternative Engine Oil Certifications

While high mileage oils may not be Dexos approved, they may meet other industry standards, such as:

API SN or SN Plus: Issued by the American Petroleum Institute, this certification ensures basic engine protection.
ILSAC GF-5 or GF-6: Developed jointly by the International Lubricants Standardization and Approval Committee (ILSAC) and the Japan Automobile Standards Organization (JASO), this certification focuses on fuel economy and emission control.

Wrap-Up: Informed Choices for Vehicle Longevity

Understanding the difference between Dexos-approved oils and high mileage oils empowers vehicle owners to make informed decisions about their vehicles’ maintenance. While Dexos certification ensures compliance with GM’s specific requirements, high mileage oils offer specialized protection for vehicles with higher mileage. By choosing the right oil for your vehicle, you can extend its engine life and maintain optimal performance.