Can You Mix 5W 20 And 5W 30? Is It Better Engine Protection?

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Last Updated on 3 months by Ollie Barker

Can You Mix 5W20 And 5W30

Do you know the difference between oil weights? If not, don’t worry! I’ve got you covered. This post is going to answer your burning question: Can you mix 5w20 and 5w30? How does this mix affect the engine?

The short answer is YES, you can mix 5w20 & 5w30 given that they’re from the same brand and API. However, experts still don’t recommend it as the engine can’t reach its peak performance with mixed oils.

The below explanation will let you know why we can do that.

Understanding Viscosity of Oils

Understanding Viscosity of Oils
Understanding viscosity of oils

Oil weight refers to a measurement of viscosity, which is a lubricant’s resistance to flow at a given shear rate. Viscosity matters because it dictates an oil’s ability to protect your engine against wear and tear. Viscosity is also what helps an oil clean your engine’s surfaces.

Let’s start with the numbers. The 5w20 is the designation of a viscosity that ranges between 10,000 cSt (centistokes) to 14,000 cSt (centistokes). The 5w30 is the designation of a viscosity between 15,000 cSt (centistokes) to 20,000 cSt (centistokes). This means 5w30 operates on a higher range of thickness than 5w20.

How Are These Two Oil Viscosities Different?

The 5w30 designation refers to the base oil viscosity, which is 10% thicker than the standard 5w20. For example, a 5w30 motor oil has an API GL-5 rating, but the same base oil could have an API SN GL-4 rating. These are just examples since there are other classification systems used in motor oils, but they’re common ones.

Even though they’re called “w” weights, these numbers don’t actually refer to weight at all. Instead, the w stands for winter. “Winter” motor oils are designed to handle longer periods of cold weather and protect against engine wear from starts and stops in cold weather. So basically, the “w” doesn’t directly correlate with weight.

In the case of an engine that uses a mix of oil weights, the 5w20 and 5w30 may show up in different percentages at different times. For example, an owner may take their car to their local mechanic for an oil change and ask for a specific weight. The mechanics will actually weigh the oil and give you a recommendation based on your engine’s needs. If you need anything over 7 quarts (7 liters), you can tell them to use 5w30 instead of 5w20.

Here is the summary:

  • What 5W20 and 5W30 have in common is that they have the same viscosity in winter. And, in cold weather, 5W oils flow more quickly.
  • The lower “20” number in 5W-20 means that it will remain somewhat thinner at operating temperature, whereas 5W-30 will offer a little thicker lubricating coating.

Why You Should Use 5W20 & 5W30 Oils

Below are some of the benefits of using 5w20 and 5w30 oil:

  • Performance:  Motor oil increases your engine’s performance. Higher flow allows your engine to flow cooler, which reduces wear on internal engine components.
  • Improved Fuel Economy: 5w20 and 5w30 oils are formulated with multiple additives that help improve fuel economy by lowering emissions.
  • Smoother Running: Motor oils are used in your engine’s pump, which helps reduce friction.
  • Reduced Wear & Tear: Reduce engine wear and tear with motor oil. This improves the efficiency and overall performance of your car.
  • Better Protection:  Motor oils protect internal engine components from wear and tear by preventing corrosion, offering lubrication for moving parts, and more.

Can You Mix 5W20 and 5W30?

Can You Mix 5W20 and 5W30
Can you mix 5W20 and 5W30?

Yes, you can top up your 5W20 with 5W30 or the other way around. Keep in mind that it’s probably not a good idea to mix the two oils, because 5W30 is thicker than 5W20 but the mixture won’t harm the engine anyway.

It’s generally accepted that mixing different weights is better than using one weight for your engine. The reasons are that it’s better for your car to have a wide range of viscosities available. Different viscosities provide different cleaning and lubrication abilities, which is important for keeping your engine clean and problem-free. What’s more, this prevents the thinning effect that happens when using a thin oil for too long.

What Ratios can I Mix 5w30 with 5w20?

Although mixing the two fluids together may not harm your engine, experts still don’t recommend it as the engine can’t reach its peak performance with mixed oils.

However, in an emergency, if you need to top off an engine with 5W30 oil that is already full of 5W30 oil with 5W20 oil, you should use more of the heavier 5W30 oil and less of the thinner 5W20 oil.

For example, in a 5W30 engine, you might use two parts 5W30 oil and one part 5W20 oil, and vice versa.

You should read the owner’s handbook to make sure you use the correct ratio if your engine allows mixing of both oils.

Is 5 W 30 Compatible with A 5 W 20 Engine?

Is 5 W 30 Compatible with A 5 W 20 Engine
Is 5W30 compatible with a 5W20 engine?

Because 5W30 oil has a greater viscosity and would be too thick for the 5W20 engine’s components, which need a thinner barrier, it might not be a good idea to use it in a 5W20 engine.

As the oil would be too thick to pass through, the engine parts would not receive adequate oil coating, which might lead to overheating, wear and tear, and oil starvation.

Additionally, the engine components would encounter increased resistance as they moved against one another.

When combined with 5W20 oil, 5W30 oil may be secure in 5W20 engines.

What Is Engine Oil 5w20 Good For?

What Is the Use of 5W-20 Oil? Since 5W-20 has a low viscosity, it is best suited for vehicles that travel frequently in colder climates and low temperatures. It can assist with engine deposits and wear and tear issues and is appropriate for light-duty gasoline and gasoline engines.

What Is Engine Oil 5w30 Good For?

Due to its viscosity, 5W30 would benefit your engine much throughout the summer. Depending on the additives added by the manufacturer, 5W30 won’t thin out rapidly when the sun is high and the engine is hot, and it will still provide considerable benefits.

The worst thing that can happen to your engine over the summer is that the oil deteriorates; this speeds up wear and could even result in engine knocking. Utilize 5w30 during the summer to prevent this.

Are There Any Benefits of Mixing Engine Oils?

Not really. Some people may benefit from mixing oils, but this is only a temporary fix. The long-term effect of mixing engine oils is that this act may lead to faster wear and tear of your engine. Also, changing the amount of base oil in your engine will require a new oil filter and an oil change. So if you’re mixing 5w20 with 5w30, you’ll probably need to change the oil again in just a few thousand miles.

Final Thought on Mixing 5w20 & 5w30

To conclude, you can mix 5W20 & 5W30 provided that they’re from the same brand and API. If you want to come up with your own oil mixture, just check the oil number of the two oils. For example, if they’re 5W-30 and 10W-30, then you can use 80% of the amount of the 5W-30 and 20% of 10W-30.

A piece of advice: if you want to prolong your engine’s life, use synthetic oils as they bring various benefits to the motor engine.

Further reading