Can You Mix 5w30 And 5w20 Oil? (Expert Opinion)

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If you’re a car owner, you may have wondered if you can mix 5w30 and 5w20 oil. The short answer is yes, you can mix these two oils, but it’s not recommended.

In this article, we’ll explain everything you need to know about mixing 5w30 and 5w20 engine oils. You’ll learn about the differences between 5w30 and 5w20 oil, how they affect your engine’s performance, and why it’s important to use the recommended oil for your vehicle.

We’ll also discuss the potential consequences of mixing oils, such as reduced engine performance, increased wear and tear, and even engine damage. By the end of this article, you’ll have a better understanding of why it’s best to stick with one type of oil.

Can You Mix 5w30 And 5w20 Oil?

As briefly answered in the intro paragraphs above, the simple answer is YES. You can mix 5W30 and 5W20.

Whether you’re topping your 5W30 engine with 5W20 oil or vice versa, you are definitely not triggering any harm or potential damage to the engine’s core components.

Yes, the oils may have different additives; hence, the difference in their weight rating. But then, that doesn’t matter, the additives in the two oils won’t blend together per se, but it still doesn’t pose any harm to any part of your car engine.

The actual question here should be, “why do you want to mix oils?” Yes, what’s your reason for wanting to mix different oils? Is your engine running low on oil, and you can’t get the exact one you’ve been using, or you just want to try out some new stuff?

Well, regardless of the reason behind your motive, you should drain out the new (irregular) oil after you have arrived at your destination and refill it with your regular oil.

However, whether you drain out the new oil and refill your old one (when you’ve got it) or not, your car would still be running fine.

In contrast, if you’re on a mission to completely change the oil you use for your car engine, we’d advise that you make extensive research regarding the potential disadvantages of not using your car manufacturer’s recommended oil.

What Actually Happens When You Mix 5W30 with 5W20?

What Actually Happens When You Mix 5W30 with 5W20

Nothing serious is going to happen. The oils will come together, but they are unlikely to blend into a single oil; so, they’d stay and flow separately. Since the two oils have the same viscosity for cold weather, they’d both flow evenly to the top ends in low temperatures.

Also, as said earlier, it would be best if the two oils you’re about to mix are from the same brand. This implies that the differences won’t be much, and that could mean better performance. Although, when you mix oils, your engine isn’t guaranteed to perform better due to incompatible additives in the oils.

5W30 will perform better if you drive in a state where the temperatures are always high. So to say, some drivers switch to thicker oils during the summer season and return to thinner oils when preparing for the winter season. If this is what you wish to practice, it is yet safe.

What is the Difference Between 5w30 and 5w20 Engine Oils?

Property5W20 Oil5W30 Oil
Viscosity at low temperaturesThinner, flows more easily in cold temperaturesThicker, flows less easily in cold temperatures
Viscosity at high temperaturesThinner, breaks down more easily at high temperaturesThicker, more robust, does not break down easily at high temperatures
Fuel efficiencyMore fuel-efficientLess fuel-efficient
Cold-start performanceBetter cold-start performance, reaches engine parts quicker, creates less dragSlower cold-start performance, takes longer to reach engine parts, creates more drag
Recommended useBetter suited to colder areasSuitable for a wider range of temperatures
Engine sizeDesigned for use in smaller enginesIntended for larger engines

Note: The information in this table is based on the sources cited in the previous prompt. It’s important to note that there may be slight variations in the properties of 5W20 and 5W30 oil depending on the manufacturer and specific formulation. It’s always best to consult your vehicle’s owner manual for the recommended oil type and viscosity.

Frequently Asked Questions

Will 5W-30 Oil Hurt a 5W20 Engine?

Somehow, all motor oils are compatible with all engines; however, every oil has some specific benefits it offers to an engine. Putting a 5w30 into an engine specified for 5w20 won’t cause any harm to the engine; however, the engine would deliver its optimal performance, and you may need to refill oil earlier than speculated.

Also, since 5W30 is thicker, it would cause the engine to use more fuel; hence, you may experience a decrease in fuel economy, and probably, a decrease in horsepower response too. Furthermore, in the long run, consistently using 5W30 instead of 5W20 can lead to fatal engine damage.

What’s The Difference Between 5w20 and 5w30 Oil?

The difference is in the viscosity of the oils; 5w30 is thicker than 5w20 when the engine is running. But, in cooler temperatures, both oils (would) have the same viscosity rating. 5W20 and 5W30 also differ based on the additives used in preparing the formula.

Is 5w30 Good For Summer 

5W30 would do your engine a lot of good during summer thanks to the viscosity. When the sun is high and the engine is hot, 5W30 won’t thin out quickly and would still deliver good benefits depending on the additives included by the manufacturer.

The worst scenario you may experience during summer is for the oil in your engine to thin out; this causes faster wear and may even cause the engine to knock. To avoid this, use 5w30 during summer.

Is 5W20 Good For Summer?

Basically, there is nothing wrong with running 5W20 during the summer. If your car is specified for 5W20, it’s all cool to stick with the oil even during the summer season. This would even cause your car’s engine to function more efficiently – as designed by the manufacturer.

Can I Mix 5w40 With 5w30?

You can mix any two oils; what happens when you mix oils is that your car’s engine won’t get to enjoy the full benefits each of the mixed oils should have delivered if used alone.

Asides from that, mixing 5W40 and 5W30 is cool, and your engine won’t be immediately affected. Notwithstanding, in the long long run, mixing oils can be harmful to the engine.


For the question, “Can you mix 5w30 and 5w20 oil?” the answer is yes, and it is best to go with oils from the same brand. Furthermore, we’d love to say that your car needs synthetic oils. Synthetics deliver a lot of benefits and promote the lifespan of motor engines.

It is also important to say that motor oils do degrade over time, and you should be careful not to use expired oil for your engine. Remember to change the oil filter for your engine – all these tips help ensure that you don’t face serious engine damage, which would likely burn a hole in your pocket.

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