5w20 vs 5w30 Oil: The Debate Continues, Here’s What We Think

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Motor oil grades can be a headache for new car owners. In particular, car owners often struggle with the 5W20 vs 5W30 comparison – which motor oil grade is the right one for them, and how are these grades different from each other?

In this post, we’ll explain oil grades to you and will help you with picking the right grade for the use cases of your car.


5W20 VS 5W30 – What Is The Difference?

5W20 and 5W30 motor oils are nearly identical when it comes to formulation. You can find either oil type in a conventional, synthetic blend, fully synthetic, high-mileage, and other styles. So no matter your needs, either oil grade can provide you with what you need.

The main and pretty much the only difference between the two oil grades is their high-temperature performance. More precisely, 5W30 oils stay more viscous at higher temperatures and are more resistant to thinning than 5W20 oils.

With that said, why does viscosity matter? Should you even care about the viscosity differences between the two oil grades?

Yes, you should indeed care. Below, we will let you know why exactly oil grades are important and which one you should go for.

5w30 vs 5w20
5w30 vs 5w20. What Is The Difference?

Why Does Motor Oil Viscosity Matter?

As you probably know, the purpose of motor oil is to reduce friction in the motor, prevent wear, overheating, as well as clean away sludge and other deposits. Well, to do this, motor oil needs to have sufficient viscosity – not too high and not too low.

Here’s why:

  • If the motor oil is too viscous, it will not be able to flow through the motor easily. Excessive viscosity may lead to oil starvation, overheating, increased wear, and catastrophic engine damage.
  • If the motor oil is too watery, then it will not be able to separate the motor’s surfaces from each other. Watery oil will flow very easily, but it won’t be able to form a protective film between the components of your car’s engine.

This is why oil should be viscous, but not too viscous.

Now, where does temperature come in?

At high temperatures, motor oil will become more watery. In extreme heat, it may become too thin for adequate lubrication. In contrast, at low temperatures, it can become too thick for adequate flow.

Some motor oils are more resistant to thinning at high temperatures and thickening at low temperatures than others.

These differences can be seen from oil grades, like 5W20 and 5W30 in our case. By looking at these grades, we can determine how they will comparatively perform in varying temperatures.

5w20 or 5w30
Pouring new oil lubricant into the car engine.

With that, we should now talk about how to read motor oil grades.


Reading SAE Motor Oil Grades

If you didn’t know, motor oil grades have been established by the Society of Automotive Engineers (SAE). SAE oil grades consist of two parts – the low-temperature rating and high-temperature rating. Below is a brief description of each rating.

  • Low-temperature rating

    The low-temperature rating is shown by the first number and letter “W” in the grade. “W” stands for “Winter” in motor oil grades.

    Low-temperature ratings go from 0W to 25W. The lower the first number, the colder temperatures the motor oil will be able to withstand before becoming too thick for normal flow. This means that, for example, 0W will stay sufficiently thin at colder temperatures than 5W motor oil.

    Our oil grades for today – 5W20 and 5W30 –are both pretty cold-resistant. They aren’t the very best oils for harsh winters, but they can hold up pretty well in milder colds. But most importantly, since the low-temp rating is the same, the two grades will have the same performance in low temperatures.

  • High-temperature rating

    The second number in the SAE grade shows the high-temperature rating of motor oil. This rating is determined by measuring the viscosity of the oil at 100 degrees Celsius (212 degrees Fahrenheit). The higher the number, the thicker the oil is and the more resistant it is to extreme heat.

    When we consider 5W20 and 5W30 grades, 5W20 is less resistant to heat and will become too watery for safe operation at a lower temperature. 5W30 will stay adequately thick at higher temperatures and will thus be safer to use in warmer climates.

    With that said, neither of these grades is great for extremely hot summers. High-temperature ratings go from 20 to 60, which puts 5W20 and 5W30 in the low-mid end in terms of heat resistance. So although 5W30 oil will be less prone to becoming watery, it’s not the best option for hot summers.


SAE Viscosity Grades For Engine Oils – SAE J300 Dec 99

 SAE Viscosity GradeHigh Shear Rate Viscosity @ 150 Degrees Celsius (mPa.s)Maximum Viscosity @100 Degrees Celsius (mm 2/s)Minimum Viscosity @ 100 Degrees Celsius (mm 2/s)
603.7<26.121.9
503.7<21.916.3
403.7**<16.312.5 9.3
302.9<12.59.3
202.6<9.35.6
25WData unavailableData unavailable9.3
20WData unavailableData unavailable5.6
15WData unavailableData unavailable5.6
10WData unavailableData unavailable4.1
5WData unavailableData unavailable3.8
0WData unavailableData unavailable3.8

Fuel Efficiency Of 5W20 Oil VS 5W30

Aside from temperature differences, which will also matter between the two oil grades is that 5W20 will be more fuel-efficient than 5W30 oil. According to Mobil, thinner oil decreases engine friction and thus increases fuel efficiency.

With thicker oil, energy loss occurs at the following engine components:

  • The oil pump because the pump will consume more energy to pump thicker motor oil.
  • The valvetrain.
  • Pistons and cylinders.
  • The crankshaft.

On the other hand, do remember that 5W20 will become too watery for safe operation at lower temperatures than 5W30 oil. At temperatures not too high for 5W20 oil, you may be able to use this oil grade and reap the fuel-saving benefits.

But with higher temperatures, you will have no other choice than to sacrifice fuel efficiency for better lubrication and motor longevity.


5W30 VS 5W20 – Which Motor Oil Grade To Choose?

Now, which motor oil grade should you choose for your car? As you could’ve already guessed, your decision will come down to the weather in your area.

Service pouring 5w20 engine oil
Service worker pouring ww20 engine oil.

Both oil grades will work well for moderate colds, which means that both will be able to lubricate your car’s engine in winter.

As for warmer seasons, 5W20 oil would probably be a more suitable choice for you if summers are pretty cool. 5W30, in contrast, would work in areas where summers are on the hotter side, but not extremely hot.


Our 5W20 & 5W30 Motor Oil Suggestions

Now, allow us to introduce you to a few motor oil options in each of the overviewed grades. Whether the right oil for you is 5W20 or 5W30, you should be able to find the right motor oil from our list.


5W20 Motor Oil Suggestions


Pennzoil Ultra Platinum Full Synthetic 5W-20 Motor...

Pennzoil Ultra Platinum Full Synthetic Motor Oil

The Pennzoil Ultra Platinum motor oil is the highest-performance oil in Pennzoil’s Platinum line. Ultra Platinum is an excellent choice for heavy use scenarios and demanding vehicles. Besides, Pennzoil advertises that this motor oil is suitable for SUVs, trucks, light vans, and turbocharged engines.

Pennzoil claims that Ultra Platinum is derived from natural gas (whereas motor oil generally is derived from crude oil). As Pennzoil writes in the product description, this allows the motor oil to contain fewer impurities than oils made from crude oil.

The temperature performance of Ultra Platinum is excellent as well. This full synthetic motor oil can ensure adequate viscosity at temperatures down to -40 and resist degradation at temps up to +400 degrees Fahrenheit.

What may matter to some people as well is that Ultra Platinum is advertised to significantly exceed the requirements of API SN-RC, ILSAC GF-5, and ACEA A1/B1 for motor protection and cleanliness.

Amazon buyers appear to be extremely satisfied with the Pennzoil Ultra Platinum motor oil. However, there have been complaints as well. The most noticeable one is that some buyers encountered additive residue at the bottom of their bottles. With that in mind, shaking well before use may be a good idea.

As a high-performance full synthetic oil, Pennzoil Platinum Ultra won’t be the right motor oil for most people. Light-duty cars probably won’t benefit from this oil in any way. It’s pretty pricey as well and thus is a waste of money if you don’t truly need its features.

But if your car is your main business tool and you want to make it more reliable and perhaps more efficient, then Ultra Platinum may be the right oil for you.

Check the price at Amazon >>


Castrol 03063 GTX MAGNATEC 5W-20 Full Synthetic...

Castrol GTX MAGNATEC Full Synthetic Motor Oil

Castrol GTX MAGNATEC perhaps isn’t as high-performance as Pennzoil Ultra Platinum, but it’s cheaper. Not only that, but if your car’s manual recommends dexos1 Gen 2-approved oil, then GTX MAGNATEC may be the right oil.

As a full synthetic oil, Castrol GTX MAGNATEC is a great choice for heavy and perhaps even professional uses.

Although this is similar to Pennzoil Ultra Platinum’s application, GTX MAGNATEC works a little bit differently.

This motor oil boasts what Castrol calls “intelligent molecules”. These molecules cling to critical engine components the moment you start up the vehicle. The molecules form a protective layer to reduce engine wear and make engine components up to 4 times smoother, as claimed by Castrol.

Although the intelligent molecules are designed to protect the engine at all times while it’s in operation, its greatest benefits appear to be more prominent during warmup. As Castrol writes, 75% of engine wear occurs during the first 20 minutes of engine warmup.

With that, if you often take short stops and start up the engine frequently throughout the day, the intelligent molecules of GTX MAGNATEC may make a big difference for you. But again, if your car is light-duty, then these benefits will be useless for your car.

Buy it at Amazon >>


AmazonBasics Full Synthetic Motor Oil, SN Plus,...

AmazonBasics Full Synthetic Motor Oil

The third and last 5W20 motor oil on the list is this full synthetic motor oil from AmazonBasics. Although it’s again full synthetic oil, it’s very different from the two previous picks.

Perhaps the most notable feature of this motor oil is that it is formulated to reduce the likelihood of low-speed pre-ignition. If you didn’t know, low-speed pre-ignition is when the main fuel charge ignites prematurely. This commonly happens in turbocharged direct-ignition motors running at low speed or high-load roads.

Although low-speed pre-ignition doesn’t happen that often, it sometimes causes severe engine damage. So if there is a way to reduce the chances of its occurrence, you should make use of it (by using this motor oil, for example).

Apart from that, the AmazonBasics full synthetic oil is formulated to protect the motor during long drain intervals. This benefit may come in handy if oil change opportunities are scarce along your typical routes.

Other than these two features, this full synthetic motor oil offers pretty basic stuff – it provides added protection from wear, reduced friction, and decreased engine deposits and exhaust emissions.

One thing to keep in mind with this motor oil is that it seems to be rebranded oil from Walmart and possibly other stores. This doesn’t make this motor oil bad in any way – buyers still have praised it very highly. But we think that it’s an important thing to know about.

Get it at Amazon here >>


5W30 Motor Oil Suggestions


Royal Purple High-Performance Synthetic Motor Oil

The Royal Purple high-performance motor oil is an excellent choice for heavy and even industrial applications. It’s pricey, but if you know that your car needs better oil than you are already using, this synthetic oil may be the right choice.

The Royal Purple oil is advertised to meet dexos1 Gen 2 and ILSAC GF-5 performance requirements and promises to deliver added protection for the motor’s critical components, especially for the catalytic emission system. Aside from that, its additives reduce friction, corrosion, deposits, wear, and it increases fuel efficiency.

If your car is running on fuel containing ethanol, then this motor oil may also work for you since it’s compatible with such fuels.

Not only that, but the Royal Purple oil is compatible with mineral and synthetic oils, so no cleaning procedures are necessary when switching from those oils to this one.

Royal Purple also advertises that this synthetic motor oil can be used in old/high-mileage motors. With that said, if you have a high-mileage vehicle, then it would probably be a better idea to buy high-performance oil specifically designed for high-mileage motors.

Notably, the Royal Purple motor oil is actually colored purple. This probably isn’t important performance-wise, but it sure makes this motor oil stand out among others.

TIP: Note that in the product description, Royal Purple writes that the oil offers protection and performance improvements for diesel and gasoline engines. However, this oil is designed only for gasoline engines – the sticker on the back specifically says “not recommended for use in diesel engines”.

Get it at Amazon >>

Royal Purple 51530 API-Licensed SAE 5W-30 High...

Shell Rotella Full Synthetic Motor Oil

Shell Rotella is an established brand on the market of diesel engine oil, but they have a few options for gasoline motors as well, including this fully synthetic motor oil.

What’s interesting about this motor oil is that it is advertised specifically for hauling and towing applications.

You won’t necessarily benefit from motor oil of this level if you are hauling frequently, but if your current oil doesn’t satisfy you, then the Shell Rotella oil may be the perfect kind of oil for you. Shell Rotella oil is formulated to provide protection in trucks and SUVs that frequently encounter extreme temperatures and conditions.

The benefits of this motor oil may be especially noticeable with stop-and-go driving and frequent stops. As we already know, frequent stops and starts are among the toughest challenges for any motor.

Notably, the Shell Rotella oil is also formulated to be used in either new or high-mileage motors. And, of course, this motor oil keeps the engine clean and has increased stability and volatility in various conditions.

Specification-wise, the Shell Rotella oil meets/exceeds the requirements of GM dexos1 Gen 2, ILSAC GF-5, API SN Plus, and a few other specifications.

It’s also nice that Shell Rotella sometime offers a rebate with a purchase of this oil. However, it appears that not everybody has been able to make use of it due to technical issues, rebate rejections, and other reasons. We can’t tell why such issues have occurred, but you should be aware of them anyway.

Get it now at Amazon here >>

Shell Rotella Gas Truck Full Synthetic 5W-30 Motor...

Valvoline High-Mileage Synthetic Blend Motor Oil

Finally, in our 5w20 vs 5w30 we have Valvoline’s high-mileage synthetic blend motor oil. This motor oil is a nice option for cars with 75,000+ mileage.

Besides, as a synthetic blend oil, this motor oil is a good choice for light- to- medium-duty applications.

Being high-mileage oil, this motor oil contains seal conditioners that treat aging engine seals to stop existing oil leaks and prevent new ones. Next, the antioxidants in the engine reduce sludge buildup, while the extra detergents bond with existing sludge and remove it from the engine’s surfaces.

Valvoline’s high-mileage oil also contains anti-wear additives that form a thick film on the engine parts to reduce friction and increase longevity.

Buyers seem to be extremely satisfied with the Valvoline high-mileage oil, but some people have received leaky bottles. This seems to be a problem with shipping rather than the product, but things could and should have been better.

Check the price at Amazon here >>

Valvoline High Mileage with MaxLife Technology SAE...

5w20 vs 5w30 – Final Words

Now, you should be able to easily choose the right motor oil for your needs. When comparing 5W20 vs 5W30 motor oil, remember about their viscosity differences we’ve talked about above.

And when shopping for the best oil for your car, don’t forget to check out the car’s user manual for recommendations.

Need to Compare Different Oil Grades?

In case you need more information, we have a few more motor oil grade comparisons published on our website. They include 0w20 vs 5w300w40 vs 5w40 or 10w30 vs 10w40. We’ll keep publishing new ones so make sure you bookmark our website and come back in a while. 


Last update on 2020-09-24 / Affiliate links / Images from Amazon Product Advertising API

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