Mixing 0w16 With 0w20: Practical Truth, Not Myths
Yes, you can mix 0W-16 and 0W-20 motor oil in most situations without causing immediate engine damage, but it is not ideal for long-term use because it alters the oil viscosity balance your engine was designed for. The resulting blend will typically behave somewhere between the two grades, which may slightly reduce fuel efficiency and engine protection compared to using the manufacturer-recommended oil.
Understanding 0W-16 vs 0W-20 Oil
The difference between these oils lies primarily in their viscosity rating system, which determines how thick or thin the oil remains at different temperatures. Both 0W-16 and 0W-20 are low-viscosity oils designed for modern engines, especially hybrids and fuel-efficient gasoline vehicles.
- 0W-16 is thinner at operating temperature, optimized for maximum fuel economy.
- 0W-20 is slightly thicker, offering marginally better protection under stress.
- Both share the same cold-start rating (0W), meaning similar performance in winter conditions.
According to data from the American Petroleum Institute (API) published in March 2024, engines using ultra-low viscosity oils like 0W-16 can improve fuel economy by up to 1.5% compared to 0W-20 under standardized testing conditions. This makes the fuel efficiency advantage a key reason automakers recommend thinner oils.
What Happens When You Mix Them?
When you blend 0W-16 and 0W-20, the result is not a precisely defined grade but rather a mid-range viscosity blend that typically behaves like a light 0W-18 equivalent. This hybrid viscosity can still lubricate your engine effectively, especially in short-term or emergency situations.
Tribology studies published by SAE International in 2023 showed that mixing adjacent viscosity grades results in predictable performance changes without sudden breakdown in lubrication. However, the engine calibration design in modern vehicles is often finely tuned to specific oil grades, particularly in engines built after 2020.
| Property | 0W-16 | 0W-20 | Mixed (Approx.) |
|---|---|---|---|
| Viscosity at 100°C | 6.1-8.2 cSt | 8.5-9.3 cSt | ~7.5-8.8 cSt |
| Fuel Efficiency | Highest | High | Moderate-High |
| Engine Protection | Moderate | High | Moderate-High |
| Manufacturer Preference | Newer engines | Wider compatibility | Not specified |
When Mixing Is Acceptable
Mixing these oils is generally safe in specific circumstances where maintaining engine lubrication is more important than maintaining exact specifications. Automotive engineers often emphasize the importance of continuous lubrication flow over perfect viscosity matching in urgent situations.
- Emergency top-offs when the correct oil is unavailable.
- Short-term use before a scheduled oil change.
- Older engines that are less sensitive to viscosity precision.
- Situations where both oils meet the same API or ACEA standards.
For example, if your car requires 0W-16 but you only have 0W-20 available during a road trip, adding a small amount is far safer than running the engine with low oil levels. The oil starvation risk poses significantly greater damage potential than minor viscosity deviations.
When You Should Avoid Mixing
Despite general compatibility, there are situations where mixing oils is discouraged due to potential long-term effects on engine performance and warranty compliance. Modern engines rely heavily on precision lubrication engineering to meet emissions and efficiency targets.
- Vehicles under manufacturer warranty requiring strict oil specifications.
- Turbocharged or high-performance engines sensitive to oil thickness.
- Hybrid engines optimized specifically for 0W-16.
- Extended oil change intervals where oil degradation matters more.
A 2025 report from J.D. Power noted that 62% of engine-related warranty claims involved improper maintenance, including incorrect oil usage. While mixing similar grades is unlikely to cause immediate failure, it may still affect warranty compliance standards depending on the manufacturer.
Expert Opinions and Industry Guidance
Automotive experts generally agree that mixing close viscosity grades is acceptable in moderation. However, they stress returning to the recommended oil as soon as possible to maintain optimal engine performance and longevity.
"Blending adjacent viscosity grades like 0W-16 and 0W-20 is unlikely to harm modern engines in the short term, but it should not replace manufacturer-recommended maintenance practices." - Dr. Elena Morris, SAE Lubrication Specialist, April 2024
Major automakers such as Toyota and Honda have increasingly specified 0W-16 for newer models to meet stricter emissions regulations introduced in 2022. This highlights the growing importance of regulatory efficiency standards in oil selection.
Best Practices for Oil Use
To maintain optimal engine health, drivers should follow a consistent approach to oil selection and maintenance. The goal is to align with your engine's design while minimizing unnecessary variability in lubrication properties.
- Always check your owner's manual for the recommended oil grade.
- Use the same viscosity grade during full oil changes.
- Limit mixing to temporary situations only.
- Schedule an oil change soon after mixing different grades.
- Ensure oils meet the same API or OEM certifications.
Maintaining consistency helps preserve the engine wear protection characteristics engineered into your vehicle, especially in newer models with tighter tolerances and advanced materials.
Frequently Asked Questions
Helpful tips and tricks for Mixing 0w16 With 0w20 Practical Truth Not Myths
Can mixing 0W-16 and 0W-20 damage your engine?
No, mixing these two oils will not typically damage your engine in the short term because they are chemically compatible. However, long-term use may reduce optimal performance since the engine is designed for a specific viscosity.
What viscosity do you get when mixing 0W-16 and 0W-20?
The resulting viscosity generally falls between the two grades, often approximating a 0W-18-like behavior, though this is not an officially recognized classification.
Is it better to use 0W-20 instead of 0W-16 if unavailable?
Yes, using 0W-20 temporarily is usually acceptable if 0W-16 is unavailable, especially for topping up oil. It is safer than running low on oil, but you should switch back at the next oil change.
Does mixing affect fuel economy?
Yes, mixing can slightly reduce fuel efficiency because 0W-20 is thicker than 0W-16. The difference is usually small-often less than 1%-but measurable over time.
Can you permanently run a mixed oil blend?
It is not recommended to run a permanent mixed blend because it introduces variability in lubrication performance and may not meet manufacturer specifications.
Do oil brands matter when mixing viscosities?
Mixing different brands is generally safe if they meet the same standards, but sticking to one brand ensures more consistent additive chemistry and performance.