Can I Mix 0W20 With 5W20

ByRobert Lozano

Yes, you can mix 0W-20 with 5W-20 oil in a pinch, especially for a small top-off. Since both are the same viscosity (20-weight) at operating temperature, it’s a safe temporary solution to avoid running your engine low on oil. However, for a full oil change, always stick to your manufacturer’s recommendation.

You’re standing in the aisle of a gas station, a quart of oil in hand. Your dashboard warning light came on, the dipstick confirmed you’re low, but they only have 5W-20. Your car’s oil cap clearly says 0W-20. It’s a classic DIYer’s dilemma.

This situation sparks immediate questions and a bit of anxiety. Will this harm my engine? Is one better than the other? We promise to clear up the confusion and give you the confidence to make the right call, whether you’re on the side of the road or in your own garage.

This complete can i mix 0w20 with 5w20 guide will break down exactly what those numbers mean, the real-world impact of mixing these two oils, and the best practices for keeping your engine protected. Let’s dive in and get you back on the road safely.

Decoding the Numbers: What Do 0W-20 and 5W-20 Actually Mean?

Before we can talk about mixing, we need to understand what we’re working with. Those numbers on the oil bottle aren’t random; they represent the oil’s viscosity, or its resistance to flow, at different temperatures. Getting this right is crucial for engine protection.

The “W” is for Winter: Understanding Cold Viscosity

The first number in the sequence, followed by the “W,” stands for “Winter.” It rates the oil’s viscosity at cold temperatures (specifically, tested at 0°F or -18°C).

  • 0W: This oil flows better and more easily when the engine is cold.
  • 5W: This oil is slightly thicker and flows a bit more slowly when the engine is cold.

Think of it like pancake syrup. When it’s cold, it’s thick and pours slowly. When it’s warm, it thins out and flows quickly. A lower “W” number means the oil does a better job of staying thin in the cold, allowing it to circulate and protect engine components faster on a cold start.

The Second Number: Operating Temperature Viscosity

The second number—in this case, “20” for both oils—indicates the oil’s viscosity at normal engine operating temperatures (tested at 212°F or 100°C).

Since both 0W-20 and 5W-20 have a “20” as their second number, they are designed to have the exact same flow characteristics once your engine is fully warmed up. This is the single most important factor that makes mixing them acceptable in certain situations.

The Key Difference: Cold Start Performance

So, the only real difference between 0W-20 and 5W-20 is how they perform for the first few minutes after you turn the key, especially in colder climates. The 0W-20 provides slightly superior protection during a cold start because it reaches critical engine parts like the camshafts and bearings a fraction of a second faster.

So, Can I Mix 0W20 with 5W20 in My Engine?

Now for the main event. You’re low on oil, and you need a straight answer. Here is our expert take, covering the common scenarios you’ll face as a car owner or off-roader. This section provides some crucial can i mix 0w20 with 5w20 tips.

The Short Answer: Yes, for Topping Off in an Emergency

If you need to add a quart of oil to get your level back to normal, adding 5W-20 to an engine that contains 0W-20 (or vice-versa) is perfectly safe. The most dangerous thing you can do is run your engine with the oil level below the minimum mark on the dipstick.

Oil starvation will cause catastrophic engine damage. Adding a slightly different but compatible oil is infinitely better. The final mixture will have a cold viscosity somewhere between 0W and 5W, which is a very minor change that your engine won’t even notice.

The Long Answer: Why It’s Not Ideal for a Full Oil Change

While mixing for a top-off is fine, you should not intentionally mix them for a full oil change. Modern engines, especially those with features like variable valve timing (VVT) or turbochargers, are engineered with incredibly tight tolerances. They rely on a specific oil viscosity to function correctly.

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Using 0W-20 is often specified to maximize fuel efficiency and ensure proper lubrication in all weather conditions. Sticking to your vehicle manufacturer’s recommendation, found in your owner’s manual, is always the best practice for long-term engine health.

The Chemistry Check: Ensuring Compatibility

The most important rule when mixing is to ensure the oils are of the same type. If your car requires full synthetic 0W-20, make sure you are topping it off with a full synthetic 5W-20. The same goes for synthetic blends or conventional oils.

Check the API (American Petroleum Institute) “donut” and “starburst” symbols on the bottle. As long as both oils meet the same modern API service standard (like API SP or SN Plus), their additive packages are designed to be compatible.

Potential Benefits and Common Problems with Mixing 0W20 with 5W20

Understanding the practical outcomes is key. While the primary benefit is clear, it’s worth knowing the minor trade-offs. We’ll explore the benefits of can i mix 0w20 with 5w20 and the potential issues.

The Main Benefit: Avoiding Engine Damage When Low on Oil

This can’t be stressed enough. The number one benefit is immediate engine protection. Topping off with a compatible oil prevents metal-on-metal contact, overheating, and severe wear that comes from oil starvation. It turns a potential engine-destroying event into a non-issue.

Potential Drawback: Slightly Reduced Cold Weather Performance

If you add a significant amount of 5W-20 to your 0W-20, you will slightly raise the cold-start viscosity. In extremely cold climates (think North Dakota in January), this could mean a marginally slower lubrication on startup. For most drivers in moderate climates, this effect is negligible.

Potential Drawback: Minor Impact on Fuel Economy

Automakers specify 0W-20 oil partly to eke out every last fraction of a mile per gallon. A thicker cold oil creates slightly more drag on internal components, which can minimally impact fuel economy. Again, for a one-quart top-off, this change will be too small for you to ever notice at the pump.

Your Step-by-Step Guide: How to Safely Mix 0W20 with 5W20

If you find yourself in a position where you need to mix, don’t just dump it in. Follow this simple how to can i mix 0w20 with 5w20 process to do it right.

  1. Step 1: Confirm Your Engine’s Recommended Oil

    First, double-check your owner’s manual or the oil cap to confirm the recommended grade. This ensures you know what you’re starting with and what you should be aiming for on your next full oil change.

  2. Step 2: Check Your Current Oil Level

    Make sure your car is parked on a level surface. Pull out the engine oil dipstick, wipe it clean with a rag, re-insert it fully, and pull it out again. Check where the oil level is relative to the “MIN” and “MAX” or “ADD” and “FULL” lines.

  3. Step 3: Add the New Oil Slowly

    Unscrew the oil filler cap. Using a clean funnel to prevent spills, add about half a quart of the 5W-20 (or 0W-20) oil. Wait a minute for the oil to settle down into the oil pan.

  4. Step 4: Re-Check the Level and Plan Your Next Steps

    Re-check the dipstick. Add more oil in small increments until the level is at or just below the “FULL” mark. Be careful not to overfill, as this can cause its own set of problems. Once done, make a mental note or a physical one in your maintenance log that you’ve mixed oils.

Best Practices and Long-Term Care Guide After Mixing Oils

You’ve successfully topped off your engine and saved the day. Now what? Following this simple can i mix 0w20 with 5w20 care guide will ensure your engine stays happy in the long run.

Don’t Make It a Habit

Treat mixing as a temporary fix, not a new routine. Your engine was designed for a specific oil viscosity, and using it consistently is the best way to ensure longevity and performance. Always prioritize using the recommended grade.

Consider an Earlier Oil Change

If you added a quart or more of the “wrong” viscosity, it’s a good idea to move up your next scheduled oil change. This will flush out the mixed-viscosity oil and restore your engine’s lubricant to the exact factory specification. It’s cheap insurance for your engine’s health.

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Listen to Your Engine

After topping off, pay attention to your vehicle. You are unlikely to notice any difference, but it’s always good practice. Listen for any new noises on startup, especially in cold weather. Any unusual sounds like tapping or ticking could indicate a lubrication issue, though this is extremely rare from simply mixing these two similar oils.

Sustainable and Eco-Friendly Oil Management Tips

Being a responsible DIYer means thinking about the environment. Smart oil management is a key part of a sustainable can i mix 0w20 with 5w20 approach.

Reducing Waste by Topping Off Smartly

By correctly topping off your oil, you avoid unnecessary oil changes and reduce the amount of waste oil generated. It’s an eco-friendly can i mix 0w20 with 5w20 practice that saves you money and lessens your environmental impact.

Proper Disposal of Used Oil and Containers

Never pour used oil down the drain or on the ground. A single quart of oil can contaminate thousands of gallons of water. Store your used oil in a sealed container (like the empty one the new oil came in) and take it to an auto parts store or a local recycling center. Most will accept it for free.

Frequently Asked Questions About Mixing 0W-20 and 5W-20

Will mixing 0W-20 and 5W-20 void my car’s warranty?

For a small top-off in an emergency, it is extremely unlikely to cause any issues that would lead to a denied warranty claim. However, consistently using the wrong oil or intentionally mixing for a full oil change could give a manufacturer grounds to deny a claim related to engine lubrication. Always stick to the recommended grade to be safe.

What happens if I mix them 50/50?

If you mix them in equal parts, you’ve essentially created an oil with a cold viscosity of around “2.5W-20.” The engine will run perfectly fine, as the operating viscosity is still 20-weight. You’ll just have slightly less cold-start protection than 0W-20 but more than 5W-20.

Is it better to mix in 5W-20 or run the engine low on 0W-20?

It is always, without question, better to mix in the 5W-20. Running an engine low on oil is one of the fastest ways to destroy it. The minor difference in cold viscosity is insignificant compared to the catastrophic damage of oil starvation.

Can I mix different brands of 0W-20 and 5W-20?

Yes. As long as both oils meet the same API service specification (e.g., API SP) and are the same type (e.g., full synthetic), it is safe to mix different brands. Oil manufacturers design their additive packages to be compatible with one another.

Final Thoughts: Your Engine is in Good Hands

So, can you mix 0W-20 and 5W-20? The answer is a confident yes—for emergency top-offs. It’s a safe, practical solution that prioritizes the most important rule of engine care: never let it run low on oil.

You now have the expert knowledge to understand the “why” behind the rule. You can confidently grab that bottle of 5W-20 to get you home, knowing your engine is protected. For your regular maintenance, stick to your owner’s manual. It’s the simplest of all the can i mix 0w20 with 5w20 best practices.

Keep checking that dipstick, stay on top of your maintenance, and drive with confidence. Your engine will thank you for it.

Robert Lozano
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