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0W40 Vs 5W30: 4 Key Differences + 4 FAQs

December 1, 2021

Wondering what the real difference between 0W40 vs 5W30 oil is? 
For example, which of these oil weight options offers a better fuel economy?

A 0W40 vs 5W30 comparison should answer the question.
And that’s exactly what we’re going to do.

In this article, we’ll tell you about each motor oil, perform a detailed 0W40 vs 5W30 comparison, and answer some related FAQs.

This Article Contains:

Let’s start!

0W40 Vs 5W30: What Are They?

0W-40 and 5W-30 are SAE multigrade oils often used in gasoline and diesel engine cars. They’re known for their performance in both hot and cold temperature situations. 

Both the gasoline and diesel engine car oils are formed from a combination of base oil with additives such as detergents and antioxidants.

Of the two, 5W-30 oil is a popular oil weight (viscosity) available in synthetic, semi-synthetic, and conventional oil forms. 0W-40 engine oil isn’t as popular because of a broader temperature range suited to more extreme temperatures. 

Now that you know what they are, let’s do a comparison and oil analysis of the two oil viscosity kinds.

4 Ways To Compare 0W40 Vs 5W30

Here are some easy ways to compare these two different oil varieties:

1. Low Temperature Viscosity

It’s very easy to determine the motor oil viscosity (thickness) from the SAE number. The number before the W oil letter denotes the oil viscosity at a low temperature. If this number is high, the oil has a higher viscosity, and if the number is lower, the oil has a lower viscosity.

From the SAE number, we can tell that the cold temperature viscosity of 0W-40 is low (zero before W oil letter), implying it’s thin, and the oil flow will be faster. This is helpful during cold startups, when the oil temp is low and the engine hasn’t warmed up.  

In comparison, 5W-30 has a higher viscosity at low temperature (5 before W), implying it’s a thicker oil than 0W-40, and the oil flow won’t be as effective in low, extreme temperatures.

2. High Temp Viscosity

The number after the W oil letter shows us the motor oil viscosity at the engine’s operating temperature. If the number is high, the better resistance the oil will have against becoming a thinner oil at high temp (operating temp).

From the SAE numbers, we can tell that 0W-40 oil has a higher number after ‘W’ than the 5W-30 oil. This implies that 0W-40 oil offers better resistance to thinning and thermal breakdown, making it a recommended oil for high temp regions.

3. Suitable Temperature

Multigrade oils are designed to work in the different ambient temperature conditions of regions around the globe.

Since both 0W-40 and 5W-30 are winter-grade oils, they’ll work effectively in cold temp regions. 0W-40 oil flow can normally go down to -40℃, whereas 5W-30 oil flow can go down to -35℃.

When it gets hot, 0W-40 oil shows better performance than 5W-30, with the ability to perform well up to +40℃. 5W-30 motor oil only flows normally up to +35℃. This implies that 0W-40 may be well-suited to engines that run at a higher operating temp.

The bottom line is 0W-40 is well suited for extreme temperatures, both hot and cold, while 5W-30 is a recommended oil for warmer winters and summer.

4. Fuel Economy

The kind of motor oil you use affects your car’s oil consumption. 

Mineral or conventional motor oil tends to have a higher oil consumption than synthetic motor oil. They also break down faster than synthetic oil, requiring more frequent oil change sessions.

0W-40’s fully synthetic motor oil form will offer better fuel economy than 5W-30’s synthetic blend or conventional oil form. 

You can also determine the fuel economy from the oil weight (viscosity). Thinner oil tends to be economical in oil consumption and can help improve fuel mileage.

With that said, both the oils offer excellent fuel economy as they maintain a good level of thinness. However, 0W-40 motor oil is the better high mileage oil as it can maintain a good level of thinness over a slightly better hot and cold temperature range.

5. Price

The prices of the different oil types vary from manufacturer to manufacturer. For example, Mobil, Castrol, Premium oils, Chevron, Spec Oil, etc., will set different prices for their 0W-40 and 5W-30 engine oils.

But on average, both the 0W-40 and the 5W-30 engine oil prices range from $20- $28. Note that the cost of conventional 5W-30 oil is often lower than full synthetic 0W-40 oil.

Just make sure that you buy from an authorized dealer to get the right engine oil that can protect your car from severe engine wear.

With the comparison done, let’s answer some FAQs.

4 FAQs On 0W-40 And 5W-30

Here are the answers to some FAQs related to 0W-40 and 5W-30 oils:

1. Can I Mix 0W-40 With 5W-30 Engine Oil?

Yes, if your car manufacturer approves it. 
If not, you should only use the approved oil. 

0W-40 and 5W-30 oils can be combined because 5W-30 is thicker oil than 0W-40, and the extra, lower viscosity will make the start-up oil flow easy and efficient. 

Temperature also plays a vital role in deciding if you can mix them. Both the oils are winter oils, so they’ll work well in cold temp regions like Europe. However, the 0W-40 alone will perform better due to its ability to stay thin down to a low temperature of -40℃.

Note: Mix only the different oil grades and never the oil brands. And it’s best to use only recommended oil in your owner’s manual to ensure your rod bearings and timing gears are correctly lubricated.

2. What Is Synthetic Motor Oil?

Synthetic oil is an engine lubricant made up of artificially made chemical compounds. These artificially made compounds are produced by breaking down and then rebuilding petroleum molecules. 

This process of making synthetic oil is very different from conventional oil (mineral oil), which is made using refined crude oil. 

Synthetic oil can be of two kinds, fully synthetic or synthetic blend, and can be obtained from multiple base types.

Full synthetic oil uses a synthetic base stock, uniquely designed molecule by molecule with no use of petroleum. However, it includes additives that are meant to help with oil degradation.

On the other hand, a synthetic blend is a mix of conventional motor oil and synthetic base stocks. The synthetic base stock addition to the conventional oil provides a bit more protection from engine wear than just the conventional oil.

3. 0W40 Vs 5W30: Which Is The Better Oil Weight?

If you see our oil analysis and comparison, you’ll know there’s no better weight oil option for your car. It all depends on your requirements and the temperature of the place where you live. 

You must consider if:

With that said, 0W-40 is a thinner oil than 5W-30, an ideal oil weight for extreme temperatures, both winter and summer. On the other hand, 5W-30 works well for warm winters and summers because it’s a thicker oil than 0W-40.

4. What Is Base Oil?

Base oil is used to manufacture motor oil by refining crude oil. 

Chemical substances like additives are added to a base oil to meet the standards needed for motor oil.

Final Thoughts

Whether you wish to go for 0W-40 or 5W-30 or a different oil, the easiest way to determine the correct engine oil weight is by checking your owner’s manual. 

And if needed, you can always rely on a mechanic to figure out the correct weight oil or the recommended oil by your manufacturer.

Speaking of mechanics, RepairSmith can be your solution to all your motor oil needs. We’re a mobile auto repair shop and maintenance solution, available 7 days a week.

We can help you with an oil change, oil filter replacement, oil pressure check, or other car and engine wear repairs. If you’re not sure of your car’s approved oil type or the kind to offer high fuel mileage, we can help you figure it out.

Reach out to RepairSmith, and our ASE-certified mechanics will help you with your motor oil or engine wear issue right in your driveway!