5W20 vs. 5W30 Oil | What’s The Difference & Which Is Better?

If you have ever gone to the auto parts store to purchase motor oil, you might have seen many different numbers on the bottles. There are many kinds of engine oil, and choosing the right one can be confusing. Some oils only have one number, while others have two numbers on them. Some of the most common types of engine oil you will find are 5W20 oil and 5W30 oil. So, what’s the difference between the two?

5W20 oil and 5W30 oil have some key differences, and your vehicle may require one or the other. Putting the wrong type of oil in your car engine could have bad consequences. Keep reading as we tell you the difference between 5W20 and 5W30 oil and which one you should use in your car.

5W20 vs. 5W30 Engine Oil: What’s The Difference?

To understand the difference between these two engine oils, you first need to understand what the numbers mean. The numbers on an oil container describe the viscosity of the oil. When you see an oil with two numbers, the oil is considered multi-grade oil. This means that the oil has different viscosities in different temperatures. The first number describes the viscosity of the oil at low temperatures or in winter — hence the ‘W’ in the reading. Technically, the winter rating refers to the oil’s viscosity in a cold engine at startup temperature. The second number refers to the oil’s viscosity at the engine’s operating temperature.

The higher the number, the more viscous the oil is. So, higher viscosity numbers describe thicker oil, while lower viscosity numbers refer to thinner oil. As you can see here, 5W30 oil will be thicker than 5W20 oil at higher temperatures. The oil’s thickness at operating temperature is the main difference between 5W20 and 5W30 motor oil. The two oils have the same thickness in cold temperatures. Similarly, 10W30 vs. 10W40 oil compares two oils with the same low-temperature viscosity but different viscosities at high temperatures. On the other hand, consider 5W30 vs. 10W30 oil. Those two oils have different viscosities at low temperatures yet the same viscosity at high temperatures.

There are some advantages to thicker oil, although there are also some cons associated with it. More viscous oil helps lubricate internal engine parts better than thinner oil. This improved lubrication comes with a tradeoff, though. Thicker oil can lead to decreased fuel economy and reduced horsepower. So, how do you know which oil to select during an oil change? The answer depends on your vehicle.

You should check your owner’s manual to determine which type of oil to use in your car. Always follow your manufacturer’s recommendation when selecting oil for your vehicle. Your engine is designed to operate optimally with a specific oil thickness. Putting the wrong type of oil in your car could cause damage and even void your warranty. If the oil is too thin, your engine might not get proper lubrication. However, oil that is too thick might cause your engine to work harder than it should.

What Is Motor Oil Viscosity?

We’ve discussed how the numbers on an oil container relate to the oil’s viscosity, but what is motor oil viscosity? Viscosity really just refers to the thickness of the oil. A low viscosity rating refers to a thinner oil, while a high viscosity rating refers to a thicker oil. The first number in the viscosity rating describes the thickness of the oil in cold weather, while the second number describes the thickness of the oil in high temperatures. The Society of Automotive Engineers (SAE) sets the standard for viscosity ratings.

Not only does viscosity describe the thickness of the oil, but it also relates to the ease at which the oil flows. Think of it like this. Water would have a very low viscosity because it is thin and flows easily. However, honey would have a high viscosity because it is thick and is slow to flow. Lower viscosity oil creates less drag and less friction on the internal engine components. This can lead to better performance and better fuel economy.

Older engines were typically built with higher tolerances for internal components, like pistons and other moving parts. Therefore, these engines needed thicker oil to provide the necessary lubrication for these parts. However, modern engines have extremely low tolerances, and these engines need thin oil. Since people also drive their cars in colder climates today than they did in the past, multi-grade oil has become a necessity for modern vehicles.

Mixing 5W20 & 5W30 Engine Oil

So, can you mix 5W20 with 5W30 motor oil? Perhaps your vehicle is filled with 5W20 motor oil, but the oil level is a little low. The only option you can find at the gas station is 5W30. Will it hurt anything if you mix the two oil types? The answer really depends on your vehicle. If your owner’s manual states that your vehicle can use either type of oil, then it should be fine to mix the two. If you do mix them, always try to use the same brand. Otherwise, different brands may have different additives in their oil that might not mix well.

If your vehicle requires one type or the other, you should not mix the two types of motor oil. Doing so could cause damage to your car’s engine. If you are faced with an emergency and need to mix the two oils to get your car going, you likely won’t experience any immediate damage. However, you should make sure to drain the oil and perform an oil change as soon as possible. This will ensure that your engine has the right oil to keep things running smoothly and efficiently.

Synthetic Oil vs. Conventional Oil

Not only does engine oil come with different viscosity ratings, but there are also different types of oil. You may have noticed that some oil is described as synthetic, while another oil is advertised as conventional. So, what is the difference? Conventional oil is sometimes called mineral oil. This type of oil is made from crude oil that has been put through a refining process. Conventional oil is available in many different weights and viscosities. For years, conventional oil was the only option available for car engines.

Synthetic motor oil is still made from natural materials. Many people believe that synthetic oil is a man-made oil, but that is not true. Synthetic oil has undergone a chemical process that makes the oil molecules more uniform in shape, and nearly all impurities have been removed. Synthetic oil is generally considered better than conventional because it provides better breakdown protection at higher temperatures. This means that the oil can provide the same amount of lubrication without failing, even at extremely high temperatures. However, fully synthetic oil is quite a bit more expensive than conventional oil.

To reach a good balance of cost versus performance, many oil companies now provide synthetic blends. These blends are a mix of both conventional and synthetic oil. They provide many of the benefits of synthetic oil without the extremely high cost. Many car owners like to use these blends, although your vehicle engine might require a full synthetic oil — especially if you have a high-end car.

Best Oil For High Mileage Vehicles

Some people believe that you should use thicker oil once your engine has a high number of miles on it. The reason for this belief is that the engine has worn, and the tolerances between the internal parts are higher. Thicker oil will do a better job of filling these gaps and lubricating the parts. However, a thicker oil can lead to decreased fuel efficiency and horsepower. Instead, you should continue to use the viscosity recommended by your manufacturer but find oil with special additives to help high-mileage engines.

Many oil companies now produce high-mileage engine oil that is designed to help extend the life of your motor. The additives in these oils help to condition and restore the seals in the engine, and some of the oils can help reduce and eliminate deposits in the engine. In addition, they can reduce sludge buildup and reduce burnoff. Here are a couple of the best high-mileage engine oils available. Castrol GTX High-Mileage 5W-20 synthetic blend is one of the best options out there for high-mileage engines. Next, Valvoline High-Mileage 10W-30 Synthetic Blend motor oil with MaxLife technology is probably the next best choice. Both of these oils can help extend the life of your engine and reverse some of the aging processes of internal components.

The Bottom Line

The only real difference between 5W20 oil and 5W30 oil is the viscosity of the oil at higher temperatures. 5W20 will be a little thinner than 5W30 when your engine reaches operating temperature. The thickness of the oil at lower temperatures is the same. As the temperature increases, the polymers in the oil expand and cause the thickness to increase. Most vehicles today require a specific oil weight, and you should always use the viscosity recommended by your manufacturer. Using the wrong viscosity could damage your oil pump or other engine components. Refer to your owner’s manual to determine what type of oil you should select at your next oil change!

Frequently Asked Questions

Should I use 5W20 or 5W30?

You might be wondering, “Can I use 5W30 instead of 5W20?” The type of oil you should use depends on the make and model of your vehicle. You should look in your owner’s manual for your manufacturer’s recommendation. Using the wrong type of oil in your engine could have unintended consequences. Using oil that is too thick could damage engine components, and it will likely lead to decreased fuel economy and horsepower. Conversely, using oil that is too thin might cause engine damage from improper lubrication.

What happens if I add 5W30 to 5W20?

If you add a small amount of 5W30 to 5W20, nothing bad is likely to happen. However, the more you add, the thicker the oil will become at high temperatures. If you mix oil from different brands, you might also be mixing in different additives. As long as your car is capable of using both 5W20 and 5W30, there should be no negative consequences from mixing these two oils. However, if your car requires one type or the other, you could cause problems by mixing the two. Mixing the two types in an emergency situation is usually acceptable, although you should perform an oil change as soon as possible to get the right oil in your car.

What are the advantages of using 5W20 over 5W30?

5W20 oil is thinner at high temperatures than 5W30, so it can provide some advantages. Since it creates less drag on engine parts, it can lead to higher fuel efficiency and slightly increased horsepower. However, you should ensure that your vehicle allows for the use of 5W20. Thinner oil does not provide the same level of lubrication as thicker oil, so you could damage your engine by using oil that is too thin. As long as your vehicle can handle it, you could see some benefits from using a thinner oil.