5W30 vs 10W30 – What’s The Difference? Which is Thicker?

When it comes to engine oil, people who change it themselves stick to the type that the car manufacturer recommended, while those who take their car to a mechanic may not even know that different kinds of oil exist. For those wondering what different oil types do, especially the differences between 5w30 and 10w30, I have prepared a comprehensive guide on the subject.

5W30 oil has a higher tolerance to cold, making it a better choice for areas with long and harsh winters. 10W30 is thicker in the winter, while both oils have the same thickness in warm weather.

How is Motor Oil Made?

The production of motor oil begins on an oil rig, where crude oil is extracted and then transported to a refinery. First, the oil is purified through a sedimentation process to remove water and large impurities. Crude oil is then repeatedly heated as it passes through a series of chambers in a process to remove even the finest particles. The resulting base oil can now be used to make regular motor oil or modern synthetic oil.

Regular motor oil is made by adding additives to the base oil that reduce friction, keep the mixture bonded, and provide better rust-preventing qualities. The oil is rigorously tested to ensure that the oil retains its characteristics. The final step is packaging and shipping out to customers.

Synthetic oil can be made out of chemically modified petroleum, but starting with the distilled crude oil is still more prominent. The making of synthetic oil is a well-kept secret that involves a series of synthesis processes and additives. The end result is the same as with regular oil, with hardly any visual differences between the two types.

What Does The Engine Oil Do?

In some ways, engine oil is like blood in a human body – it’s an essential fluid that performs a number of crucial tasks in the system.

The engine block is a metal-made construction that has to endure thousands of heat-generating explosions every minute. Just like an empty pot on the stove, without oil, the engine will quickly overheat and lose its hardness. When that happens, the valves are the first to deform, followed by the cylinder heads, crankshaft, rupture of the head gasket – essentially a total engine failure.

Oil has a high tolerance to heat and circulates through the moving parts of the engine. While it has a cooling effect, its primary job is to lubricate parts and reduce heat generated through friction. Because it’s reducing friction, it’s also significantly reducing the wear of the parts. When impurities show up in the system, the oil will circulate to the filter, where they’ll get traped.

Metal’s natural enemy is corrosion, so engine oil is built with anti-rust additives to keep the internal components from wearing down. In short, motor oil is a vital part of any vehicle with an internal combustion engine.

Engine Oil Grades

You’ve seen different markings on engine oil bottles in this form: number – w – number. These markings represent the engine oil grade:

  • The first number represents the emulated weight of oil in cold temperatures.
  • The “W” stands for winter.
  • The second number represents the weight of oil under normal/warm conditions.

The scale was made by SAE (Society of Automotive Engineers) to help owners find the right oil type for their conditions.

The significance of oil grades

Motor oil with a 0W winter rating is thin enough to operate at temperatures as cold as -40°c. The 10W grade can run at -30°c, while the 20W grade cannot operate properly below -20°c.

Motor oil with a 50 warm rating is thick enough to operate at temperatures as high as 50°c. The 40 grade can run at 40°c, while the 30 grade shouldn’t go above 35°c.

Difference between 5W30 vs 10W30

Now that we’ve gone through engine oil grades, you can easily tell the difference between 5W30 and 10W30. The 5W30 oil is thinner in the winter and can operate at -35°c, while 10W30 shouldn’t go below -30°c. Both oil types have the same summer rating of 30, making them thick enough to run at temperatures up to 35°c.

So on paper, 5W30 is better as it covers a wider range of temperatures. If we were to choose oil by that criteria, then 0W40 is an even better option, with superior tolerances on both sides of the temperature scale. It’s obvious that there’s a reason why different types of oil exist, and that you should change oil type without doing some research.

Because both oil types are tolerant to extremely cold temperatures, there’s not much of a difference between 5W30 and 10W30. If you’re living in a colder climate, go with 5W30, and if you’re in a warmer place or running an older car, go with 10W30 as it’s thicker.


How to Choose Engine Oil

The first thing to consider is the manufacturer’s recommended oil types. Modern cars can operate anywhere in the world, but there’s a huge difference in climate and temperature between Alaska and Texas. Because of that, the manufacturers always prepare a list of oil types to cover all temperature ranges.

It also has to do with how the engine is built. The diesel for example need thicker oil and use 5W40 even if the summer temperatures don’t go beyond 30°c. Some of the newer petrol engines need 0W-20, which is a much thinner oil across the spectrum.

Even though the manufacturer narrows your options, there’s still plenty to choose from. The best way to decide what oil grade you need is to take a look at the weather forecast of the warmest and coldest months of the year, and see how far the temperatures go. A few extremely hot or cold days don’t warrant changing the oil type, but if the temperature is constantly above the rating of your oil, you change the rating by 5.

If you’re wondering what brand of oil to buy, I’ll make a list of the best oil manufacturers so you can shop with confidence.

Prices pulled from the Amazon Product Advertising API on:


Can you put 10w30 in a 5w30 engine?

If the manufacturer states that 10w30 can be used in the engine, then yes, feel free to switch from 5w30 to 10w30. If your car is a few decades old, then using thicker oil will help it keep oil pressure up.

Which oil is thicker 5w30 or 10w30?

Both oils have a warm rating of 30, meaning they’re equally thick in the summer. However, the 10w30 is thicker in the winter than 5w30, making it less suitable for colder climates.

Is thicker oil better?

When the engine runs for hundreds of thousands of miles, thicker oil increases lubrication in bearing clearances that became larger over the years. If the oil is too thin, it may not be able to reach every part of the engine, so it’s uncommon to switch to a thicker-grade oil on a high-mileage car.

When to use straight weight oil?

Modern oils like the 10w30 and 5w30 are multi-grade oils because they have ratings for winter and summer. Straight weight oils have a single grade, meaning they’re built only to run in the summer or the winter. Nowadays, it should only be used in classic cars that were made prior to the invention of multi-grade oils, and never in any modern engine.


Because the differences between 10w30 and 5w30 are not drastic, switching from one to the other shouldn’t be an issue. Still, it’s worth checking what oil grades your engine’s manufacturer recommends to avoid damaging it. Use of improper oil can lead to inadequate lubrication of the engine, and that’s never a good thing.