5w30 vs. 10w30: Which Motor Oil Is Suitable for Your Car?

5w30 vs 10w30

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Back in the day, there were only single-graded motor oils sold in the market. The changes in temperature would require a vehicle’s engine to pump more or less to lubricate its essential parts.

However, as the technology in vehicle engines developed, manufacturers started to produce motor oils that can adapt to temperature changes and various engine settings. Many multi-grade engine oils such as 5w30 and 10w30 are in the market.

For this article, l will try to answer some of the frequently asked questions comparing the most popular engine oils used. 5w30 vs10w30.


Choosing Your Engine Oil - 5w30 or 10w30

The motor oil may perform in different conditions. You have to take a few considerations before buying them.

Your vehicle manual contains the manufacturer’s recommendation of the best multi-grade oil to use. Manufacturers designed motor oils to work differently in changing temperatures.

The Differences between 5w30 and 10w30

There are many multi-grade engine oils in the market. However, most owners use or choose between 5w30 and 10w30. These figures may be confusing for beginners. However, these are indicators of how an engine oil may perform when the engine starts, and while it runs.

Viscosity and Temperature (Hot and Cold weather)

Viscosity is the ability measured in a fluid’s resistance to flow. To give you a better understanding of how engine oil behaves on temperatures, here is a few points to know.

  • Thicker or heavier motor oil has slower movement than thin or lighter oils.
  • Thinner engine oil flows faster throughout the engine
  • When the temperature in the engine rises, the oil becomes thinner.
  • When the temperature in the engine goes down, the oil becomes thicker.
  • Engines with higher operating oil temperatures need viscous oils.
  • Engines with lower operating oil temperatures need less viscous oils.

You need thinner engine oil on cold weather to lubricate your engine. However, the oil becomes thicker as the temperature goes down. Thicker oil would run on the engine slowly on cold temperatures.

On the warm temperature, the viscosity of the motor oil becomes thinner faster. As any oil does, the warm temperature prevents the oil from solidifying. Thus, the fluid reaches the internal system of the engine faster at a warm temperature.

So What Do 5w30 and 10w30 Stand for?

In this case, the first number 5 and 10 indicate the flow speed or the time required for a liquid to flow at the lowest temperature. A lower number shows it’s easier to get through the internal components of the engine. It means that 5 will flow smoother than the 10.

The second number, 30, shows the engine oil's thickness once it reaches the engine’s highest operating temperature. In this case, both 5w30 and 10w30 has the same level of thickness once it reaches the engine’s highest operating temperature. 

On the high viscosity 30, 5w30 reaches the engine’s internal components faster than 10w30. So if you are going to use a 10w30 on the lowest temperature, it may take more time for the oil to squeeze into the engine’s system.  

When to Use 5w30 vs 10w30?

5w30 runs faster on a cold weather. The best time to use 5w30 for your engine is during the winter. The level of thickness doesn’t make any difference as it is identical to 10w30. That makes it even safer to mix or switch to 10w30 when summer arrives.

However, if you are going to use oil with a different level of thickness or weight, it may affect your engine’s performance.  Manufacturers recommend using the weight of oil indicated in their manuals. Now you are left only to choose which one will work better on your current temperature.

5w30 vs 10w30 high mileage and Driving Habits

Most of the vehicles today can run up to 300,000 miles. The wear and tear of an engine could differ in the location where you mostly drive. City driving on a shorter mile could cause wear and tear as much as highway miles driving. That is, city miles driving are more prone to frequent stops and start. Traffic also causes higher temperature that requires the engine to overwork.

However, a well-maintained vehicle could stand the challenges of high-mileage driving. Change your oil more often when you drive it frequently. This will help you tone your engine’s edges.

Comparing 5w30 vs. 10w30 can make no difference in this case. If you are using your vehicle too much with less attention to the regular changing of oil, you might need a more viscous oil. In this case, 10w30 is more viscous than 5w30.

To prevent high mileage problems, you need to change oils at regular intervals, except if your oil burns. You have to top oil at once. Perform compression tests. Do not wait for your change oil schedule when you find that your engine is losing pressure.

Remember to check on your oil filter to help your oil keep your engine clean.

Viscosity and the Engine Oil Type

There are three main types of engine oils.

Conventional Oil

Conventional oils are crude oil (in its purest form) extracted and filtered from the ground. Known for resistance to heat, conventional oils protect the engine longer than synthetic and full synthetic oils. Generally, conventional oils are thicker than synthetic ones. Oils that fit older engines are conventional or classic ones. You can expect frequent change of oil every 3,000 miles.

Synthetic Oil

Manufacturers produce synthetic oils to adjust to the changing temperatures while maintaining its viscosity. It composes several additives aside from the base oil that prevents it from breaking down, clean the engine, prevent contaminants, and more. That means synthetic oil performs and cleans better than conventional oil. Its viscosity index ranges to 150.

Full Synthetic Oils

Full synthetic oils are the most expensive oil. Its viscosity could range up to 200 while maintaining its thickness on high temperatures. Ideal for new vehicle engines, full synthetic oils are 100% synthetic. It is 100% human-made. You won’t find organic components or hydrocarbons in a full synthetic oil.

Is It Harmful to Mix Synthetic and Conventional Oils?

Although it is not a good practice to regularly mix synthetic and conventional oils, doing so once would not harm your engine. It is generally safe to switch between synthetic oil and vice versa. Much refined oil offers better benefits than using conventional oils. It lubricates and cleans better than conventional oils. Why? Manufacturers invested in extensive research to upgrade the oil's performance, especially on high-mile engines.

Hence, mixing 5w30 oil with 10w30 when the season changes doesn’t affect your engine. Remember that the two have the same level of thickness.

However, upgrading your oil for an old engine may have risks. Its seals and gaskets are not as tight as new engines. That’s why older engines need thicker oils that conventional oils only do. However, make sure that you change your oil now and then. Using synthetic oils cleans better. However, its cleaning power may remove the deposits that serve as sealants to older engines.


The Roles of Motor Oil for Your Vehicle

Aside from lubrication, motor oil plays an essential role in keeping your vehicle engine in shape. Since the engine has components that are in constant motion, the right motor oil would help minimize friction in your vehicle. It keeps your engine cool at high temperatures. Lubrication protects your engine parts from wear and tear.

Most motor oils today are made up of detergents and dispersants aside from base oils. Base oils have the degree of solvency that keeps the internal engine parts clean. Detergents adhere to hot components like piston rings. Dispersants sort contaminants and suspend them in the fluid.

Your motor oil will serve as a sealant, preventing combustion gases from entering the combustion chamber. A frequent oil change helps your sump from getting contaminated with hot gases, therefore, maximizing horsepower.

Because of its sealing function and incompressibility, motor oils could prevent a sudden rupture or shock from the engine’s mechanism. 

What Happens When You Use the Wrong Type of Motor Oil?

Choose the best motor oil for your vehicle to utilize these motor oil benefits and maximize your engine’s performance.

Oil Leaks

For older engines, the last thing you want is to develop oil leaks. Older engines work effectively on conventional motor oils. You need oils that can squeeze into hard-to-reach areas that older engines have. While it doesn’t necessarily damage your engine when you use synthetic oils, it may leave a few drops of oil or cause a burning smell when you drive.

Burnt Oil

Motor oils break down when the viscosity is not enough to lubricate the engine parts. In turn, engine parts may wear and tear due to excessive friction.

Starting Your Vehicle on a Cold Temperature

Thick motor oils on cold-weather flow more slowly. Thicker oils will require the engine to work harder.

Reduced Fuel Economy

When your engine is working too hard because your motor oil has high resistance, your engine consumes more fuel than it should.

Ticking Engine

If you choose thinner motor oil on the wrong condition, you might find your engine ticking. The ticking sound on the engine when you are just starting is an indication of poor coating and lubrication due to wrong viscosity weight. At this point, the valve lifters and valves hit each other.


Final Thoughts

In general, choosing 5w30 would only make a difference when you use it at a cold temperature. 5w30 flows faster than 10w30. However, the two variants have the same level of thickness. It makes the switching unnoticeable at all. 10w30 oils would require your engine to warm up first before starting to lubricate your engine. However, 10w30 is more viscous than 5w30. You can use them both, only that you have to weigh on the factors like the temperature, mileage, and driving activities.


About the Author JamesL Davis

James is a certified auto technician specializing in commercial vehicles. With 30 years of experience under his belt, James has encountered almost every type of automotive issue there is! Besides his day job at the repair shop, he is also an amateur race car driver.

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