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5W30 Vs 10W30: Key Differences + 4 FAQs

November 29, 2021

5W30 vs 10W30 — what are they?
Which one is the better engine oil?

The easiest way to make a decision and learn about these oils is to compare them.
Fortunately, that’s exactly what we’ll be doing!

In this article, we’ll do a thorough 5W30 vs 10W30 comparison, tell you what they are, and answer some frequently asked questions for added clarity.

This Article Contains:

Let’s start!

5W30 Vs 10W30: What Are They?

5W-30 and 10W-30 are multigrade oil types that are also found as conventional oil and synthetic oil variants. They’re used in engines to reduce friction between moving engine parts and increase engine life. 

Since they’re a multi grade oil type, they contain viscosity improvers and two oil viscosity grades. 

The two viscosity oil grades include: 

Note: A single viscosity grade motor oil (like, say, SAE 30) doesn’t use viscosity index improvers. Viscosity improvers are what allow a multi grade oil to resist thinning or thickening in a higher or lower temperature, respectively.

With that said, let’s see how each engine oil grade holds up against the other.

5 Ways To Compare 5W30 Vs 10W30

Even though both the oils are multi grade engine oil types, there are some prominent differences between them:

1. Low Temperature Viscosity

To understand the oil’s viscosity at a low temperature, meaning anything under 0°C (32°F), just look at the first number before W in the SAE oil number. 

This number is important for your engine startup when the engine is still in the freezing ambient temperature of a colder climate. 

Now, the lower the number before ‘W’ is, the less likely the motor oil will thicken at a low temperature. 

So when you compare 5W30 vs 10W30, 5W30 oil has a lower number (5), implying the oil thins fairly in an extremely low temperature, making it a better winter engine oil than 10W-30. 

Since oil 10W-30 has a higher number before ‘W,’ it won’t flow as quickly as 5W-30 at a lower temperature.

However, note that both the engine oils, 5W-30 and 10W-30, are SAE-graded for winter performance. Since both have low winter-grade oil numbers, they both have low temperature viscosities. 

This also implies that both multi grade oil types perform relatively well in cold temperature climates when compared to other oils.

It’s also worth noting that synthetic oil formulations will hold up better in a colder temperature than their conventional oil counterparts, thanks to reengineered molecules. 

2. High Temperature Viscosity

The number after the ‘W’ denotes the oil viscosity at a high 100oC (212oF), often known as the engine’s operating temperature or ambient temperature.

When this number is higher, you get a thicker oil at a high temperature. 

Since 5W-30 and 10W-30 have an oil viscosity of an SAE 30 single grade oil, they can resist becoming a thinner oil in higher temperature conditions. That said, their hot temperature performance won’t equal that of a higher viscosity oil like 10W-40. 

3. Temperature Performance Range

Since both 5W-30 and 10W-30 are multigrade oil types, they perform well within a large temperature window.

5W-30 oil type works within -30oC to 35oC, whereas 10W-30 oil type works in a relatively smaller temperature range of -18oC to 30oC.

4. Suitable Vehicle Types

5W-30 multi grade oil is ideal for private vehicles and light-duty petrol and diesel engines. It also provides a better cold temperature start than 10W-30 oil.

On the other hand, the slightly thicker oil,10W-30, provides better lubrication for commercial vehicles and heavy-load engine cars. Even though this multi grade engine oil can be used in a colder temperature, it’s better suited for warmer weather.

5. API Ratings

The latest SAE 5W-30 and 10W-30 motor oils should meet all the requirements of API ratings.  

API ratings are an engine oil class or category founded by the American Petroleum Institute. According to these ratings, engine oil should be effective enough to protect the engine piston from any deposits created by combustion.

However, you must confirm beforehand (to ensure the rating suits your vehicle) because it can vary depending on the oil brand.

4 FAQs On 5W30 Vs 10W30

Here are some FAQs related to both the multi grade engine oil types:

1. Can I Mix The Engine Oils 10W-30 And 5W-30?

When two oil kinds have a similar synthetic and viscosity, like 10W-30 and 5W-30, you can mix them.

However, it’s always best to stick to the viscosity oil requirements mentioned in the engine manual. Only mix the oils if the manual approves, or if it’s an emergency. 

2. Should I Use Thicker Oil In An Older Engine?

We recommend using a high mileage oil type instead of higher viscosity or thicker oil for an older engine. 

Thicker oil may be able to increase the oil pressure in an older engine of old car models, but it doesn’t necessarily apply to an older engine in modern car models made in the last decade or so. 

With advancements in oil chemistry, oil filters, and machining designs, damages and engine wear from friction have been reduced and affected oil passages aren’t as wide. So a higher viscosity oil may not help increase the oil pressure, but a high mileage oil can.

3. Can I Use 10W-30 Instead Of 5W-30 Motor Oil?

If it’s a recommended viscosity oil for your engine, then yes. 

Otherwise, it’s always better to use the manufacturer-recommended viscosity oil or weight of motor oil for better lubrication and protection from engine wear. 

Using a higher viscosity oil than needed may result in increased drag and extreme oil temperatures. That’s because a high viscosity oil can’t effectively transfer heat as well as low viscosity oil.

On the other hand, a lower viscosity oil (thinner oil) than recommended for your car engine will make the oil flow really quick when the vehicle is in motion. As a result, the internal engine parts may contact one another (metal-to-metal contact), causing engine wear due to friction.

Moreover, the right motor oil not only protects your engine components but will also give you maximum fuel economy and efficient oil consumption.

4. Which Is Better: 5W30 Vs 10W30?

Both 10W-30 and 5W-30 multi grade oil options are excellent because there’s no best oil. It all depends on your car’s needs, where you live, and the climate or temperature there. 

So to determine the better engine oil option for you, it’s crucial to understand how 10W-30 and 5W-30 oils work in a colder climate or a hot one. 

5W-30 is ideal for any season and offers supreme protection in a cold temperature region. It also provides you with excellent fuel economy as it creates only a minimal drag on the moving engine components. 

On the other hand, 10W-30 is best suited for cars with heavy load diesel or petrol engines.

Final Thoughts 

5W30 and 10W30 motor oil are pretty similar in their performance at operating temperature. But when it comes to low-temperature performance, 5W-30 oil performs better because of its low viscosity in a colder climate.

However, deciding which engine oil to use depends on your location, climate, oil consumption needs, and other requirements. 

Remember, it’s best to go with the engine oil recommendation by your manufacturer for better lubrication and protection from engine wear.

If you feel an oil change is long due, consult a professional or mechanic. 
And in case you’re looking for a good mechanic, RepairSmith can be the answer. 

RepairSmith is a mobile auto maintenance and repair solution available all week via an easy online booking process. We can perform an oil change, help you decide if you need thicker or thinner oil, identify engine wear and maintain engine parts, and provide most repair services directly on-site.

Reach out to RepairSmith, and our ASE-certified mechanics will swing by wherever you are with help!