Oil moves through the engine as the car moves, protecting it from damage. Nowadays, motor oil comes in a wide range of different types, weights, and mixtures. The two most popular viscosities in engines today are 10W30 and 10W40. There are a few differences in viscosity between them.
In this study, I’ll carefully examine the differences between engine oils and give you sound advice on which is best for your car. Our goal is to clean up any confusion about whether you can use 10w 40 instead of 10w 30.
What Is the Difference Between 10w30 and 10w40 Motor Oil?
As we discussed in the previous article 75w90 vs 80w90, oils can change colors to fit different temperatures. But what makes them work, and when should you pick one over the other?
When it’s cold, you should use 10W-30 oil. It acts like a thinner SAE 10 oil, ensuring your engine starts quickly. It works like a thicker SAE 30 oil when it gets hot, which keeps your engine running smoothly.
This oil can handle temperatures as low as -30°C/-22°F. Don’t worry about starting up in the cold even if your vehicle is parked outside all night.
Now, 10W-40 oil works fine in cold weather, too, but when it gets warmer, it’s great. It works well in cold temperatures. But at about 100°C/212°F, it stays thicker when it’s hot. That’s great for hot summer days.
Both 10W-30 and 10W-40 are like shapeshifters, thanks to polymers. These little things help the oil change its thickness as the temperature changes. You’ll find these oils in regular or high-quality synthetic versions.
Getting to Know Oil Viscosity for Your Car’s Engine
When people talk about viscosity, they mostly talk about how thick a liquid is. Just think about how much less viscous oil is than water. When poured, water flows more quickly than oil. This is because oil has a higher viscosity.
Now, how oil reacts to weather is another thing that affects its viscosity, which is more than just its thickness. If you store oil in the refrigerator, it hardens over time into a thick, waxy consistency. This shows how temperature changes the thickness of oil. As the temperature drops, oil gets more viscous, and as the temperature rises, it gets thinner. Both depend on each other.
This is why oil grades are essential. Before selecting oil, we consider its viscosity and performance characteristics based on its grade.
Understanding the Type of Oil
Let’s talk about the numbers that stand for different types of oil, like 10W30 and 10W40. If the number is less than 10, the oil moves more slowly in colder places. 5W oil flows faster than 10W because smaller numbers can be moved more quickly when it’s hard.
The second number indicates how well the oil flows in summer. Oil with a higher second number performs better in protecting against very high temperatures and pressures.
The only difference between 10W30 and 10W40 oils is how they respond at higher temperatures and pressures. As the temperature rises, 10W40 becomes thicker.
|Viscosity at low temps
|Flows slightly better
|Flows slightly thicker
|Viscosity at high temps
|Thins out more
|Maintains a bit thicker consistency
|Colder climates, mild weather
|Hotter climates, high temperatures
|Cold weather performance
|Good for cold starts
|Effective for cold starts
|Hot weather performance
|Adequate, might thin at high heat
|Better thickness in extreme heat
|Good protection in milder temps
|Enhanced protection in high heat
When Should You Use 10W30 and 10W40?
So, is 10W-40 oil good for high mileage? In cold places, it’s excellent to have 10W30 oil. It performs well even in hot engine conditions and helps cool the engine down when it’s cold outside.
In hot places, 10W40 is always the best pick. t enhances engine safety, especially if the engine tends to run hotter than usual, as it is designed to handle higher temperatures.
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What Happens When Mixing 10W30 and 10W40 Oils?
- Mixing different oils reduces oil pressure, increasing the risk of engine bearing failure, especially at higher speeds.
- Using a mixture of oil at a different temperature and thickness could weaken your engine and could void your car’s warranty.
- Mixing them could damage the engine because they are designed for different situations, even if they work the same in cold weather.
- If you need to mix different types of oil quickly, it’s better to have additional oil available. This will help keep your engine running smoothly in the future.
Choosing the right engine oil grade is essential for keeping smooth internal operations. The most significant difference between 10W30 and 10W40 viscosities is their thickness when the temperature is higher. Both move similarly when it’s cold, which protects the engine.