Blog Car Care Advice What Does 10W-30 Oil Mean? (+How It’s Useful to You) 
Car Care Advice

What Does 10W-30 Oil Mean? (+How It’s Useful to You) 

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10W-30 is a popular multi-grade oil commonly used in heavy-duty diesel and gasoline engines. 

But what does 10W-30 oil mean?

We’ll go over the details of 10W-30 oil, including its uses and benefits. We’ll also help you determine whether or not this oil is a good fit for your car’s engine.

Let’s begin!

This Article Contains: 

What Does 10W-30 Mean in Oil?

10W-30 signifies the oil’s viscosity grade, which tells you how the oil flows at certain temperatures. This is vital information for choosing the best lubricant for your car. 

Now, let’s break this number down. 

In 10W-30: 

So a lubricant with this oil grade can smoothly flow at varying temperatures without causing too much friction between the engine parts. 

But do these grades really matter?

Why Are Viscosity Grades in Oil Important?

Engine oil grades help determine how oil will perform in different temperatures, ensuring you use the right lubricant meant for your car model and the local climate. 

For example, a thin oil with a lower grade (low oil weight) can lubricate the engine parts and move freely in cold-temperature conditions. Meanwhile, thicker oil (high oil weight) will keep the engine parts well-lubricated when the weather is hot. 

Moreover, a modern engine with a small clearance (the gap between the engine’s moving parts like the bearings and the crankshaft) works well with thinner oil. An older car engine with a large clearance works better with thicker oil. 

So, who decides these grades, and on what basis?
Oil’s viscosity grades are assigned by the Society of Automotive Engineers (SAE) J300. The oils are graded based on their resistance to flow across a range of temperatures. 

Before the 1950s, SAE monograde (single-grade) oils were quite commonly used, but with the advancement of cars, newer oils were formulated. 

The two common types of engine oil grades you’ll find are: 

Note: Multigrade oils often have viscosity improvers (additives that improve the lubricant’s density). For example, SAE 10W-30 multi-weight oil has the properties of SAE 10 oil, which offers a good low-temperature performance. Additionally, viscosity improvers provide the attributes of SAE 30 oil, allowing 10W-30 to also perform decently in a higher-temperature climate.

Now that we’ve covered what 10W-30 multi-grade oil means, let’s explore its uses and benefits. 

What Is 10W-30 Oil Used For?

10W-30 is best suited for heavy-duty gasoline, biofuel, and diesel engines since it’s a slightly thicker oil that can handle a heavy load. It can withstand hot and cold temperatures without compromising engine performance. This lubricant also protects your car’s engine parts like pistons and prevents engine deposits.   

Here are some other benefits of using 10W-30 oil in your car:

Note: While 10W-30 oil can provide good high-temperature performance, you should use it only if it’s recommended for your engine or as per your mechanic’s advice.

Still have some unanswered questions about 10W-30? 
Let’s check out the FAQs to clarify them.

5 FAQs about 10W-30 Oil

Here are answers to some common queries about the 10W-30 oil:

1. Is 10W-30 Oil a Synthetic Oil?

Not always. 

10W-30 engine oil is available in several variants, such as conventional (mineral oil), synthetic, and synthetic blend oil. Here’s how each variant differs from the other:

That said, always consult with your mechanic before switching between synthetic and conventional oil during an oil change

2. Is 10W-30 Oil Good for High-Mileage Vehicles?

Yes, 10W-30 motor oil is a decent high-mileage oil for older engines. 

Older engines with more than 75,000 miles usually require thicker oils to properly lubricate critical engine parts. Fortunately, 10W-30 multi-weight oil is dense enough to reduce friction between gears and metal surfaces, reducing the chances of wear. 

It also improves fuel economy and oxidation resistance while reducing the oil consumption of old cars. Moreover, it helps prevent oil leaks, sludge, and corrosion build-up — something quite common with aged vehicles. 

However, before buying a higher-viscosity oil, check your owner’s manual to ensure you choose the right oil for your car engine.

3. How Is 10W-30 Oil Different From Other Oils?

The oil differs in thickness or density. If you compare SAE 10W-30 weight oil to a higher-viscosity lubricant like 10W-40, the latter will perform better at a higher temperature. 

But, since 10W-30 is thinner than 10W-40, it flows more smoothly without creating friction caused by engine drag (a situation where the engine robs its own power to move the car forward).

As a winter lubricant, 10W-30 performs well in colder temperatures. However, a lower-viscosity oil such as 5W-30 will be much more effective for cold start-ups in winter. 

Overall, 10W-30 is best for heavy-duty gasoline or diesel engine vehicles or for use in regions with mild, cold weather conditions. 

Tip: As a vehicle owner, ensure that the oil you’re adding is certified by the Society of Automotive Engineers (SAE) and the American Petroleum Institute (API SP). This way, you know the lubricant is authentic.

4. Can I Use 10W-40 Instead of 10W-30 Oil?

No, you shouldn’t. Your car requires oil with the appropriate engine oil viscosity grade to lubricate and improve the engine’s performance. Switching the recommended oil with another variant can lead to engine wear in the long run.

Many cars with a modern engine require low-viscosity oils, and switching to a heavier lubricant can affect the engine’s performance. 

That said, some vehicles may allow flexibility in switching between different types of motor oils, but it’s best to check with your mechanic before making the switch. 

5. Can I Mix 10W-30 with Other Engine Oils?

Yes, but only in emergencies

You can mix 10W-30 with another lubricant, like 5W-30 or 10W-40, as their engine oil viscosity is close.   

But if you have concerns about mixing multi-viscosity oils, consult a professional to be 100% sure. After all, adding engine oil should improve fuel efficiency and elevate your engine’s performance. If it doesn’t do that, mixing them may be counterproductive. 

Also, since each engine oil varies in density, you must add the right proportion of oil for the engine to benefit from it.

Get Routine Motor Oil Refills with AutoNation Mobile Service

10W-30 oil usually performs well in hot and cold weather. But it may suit only certain cars or climatic conditions.

If you’re unsure whether your car needs 10W-30 oil, you can call AutoNation Mobile Service mechanics to verify and perform the required oil change. 

We’re a mobile auto repair solution that offers competitive, upfront pricing and a range of maintenance services. We also provide a 12-month | 12,000-mile warranty on all services, including gear oil changes.