Each year, with the introduction of new vehicles, the number of engine oil viscosity options available to consumers increases. However, in most cases, vehicle owners do not need every weight of oil offered by manufacturers.
Choosing between 0w40 and 0w20 is a common choice that may seem difficult to make but can be done quite easily. Below, ten differences between 0w40 and 0w20 engine oils will be discussed to provide the car owner with knowledge that can be used to make this decision easier.
One of the most popular is 0w20 engine oil. Read below to learn about this type of oil, as well as why many people choose it over other brands.
What Is 0W20 Oil?
0w20 engine oil is a blend of mineral and synthetic oil that is specially formulated to offer outstanding lubrication and protection. 0w20 oil will help to keep your engine running smoothly and efficiently, even in cold weather conditions.
0W20 And Other Oils
While the viscosity of 0w20 engine oil can be compared and contrasted with other types of oil, it is unique because it offers improved high-temperature stability, shear resistance, and oxidation compared to other models.
This type of oil is best used in cars that are made by high-end manufacturers. For example, the engines in certain Lexus and Audi models require 0w20 oil for optimal performance. Due to its viscosity rating, 0w20 engine oil does not work well when temperatures drop below zero degrees Fahrenheit.
What is 0w40 oil?
0w40 engine oil is a specific weight of oil, which gets its name from its viscosity rating under low temperatures (the “0”), the lower end of the range for this viscosity (the “w” that stands for winter), and the highest end of the range for this viscosity (the “40” which means the flow at high temperature).
Viscosity is the measure of an oil’s ability to resist flow. The lower the number (as with 0w20), the less resistance it has to flow, and the faster it can drain from areas where it’s not needed (such as bearings).
The higher the number (as with 10w40), the more resistance it has to flow, and the slower it drains from those areas. The lower viscosity of the oil is better for cold starts because it can get to bearings faster.
The higher viscosity of the oil is better for high-temperature operation because it drains slower in those areas.
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Oil Viscosity Grades
Motor oil is graded according to its viscosity. The common grades used by car manufacturers are 0w20, 5w20, and 10w30. This means that the oil has a low weight as compared to other oils.
This number denotes the standard measure for this factor which is expressed in units of centistokes or stoke.
Ten differences between 0w40 and 0w20 engine oils
1. Top-end oil pressure
0w20 has a higher top-end oil pressure, which means it will lubricate the engine better at high speeds and RPMs. 0w40 has a lower top-end oil pressure, which gives it the benefit of low-speed protection.
2. Cold weather viscosity
0w20 has a lower cold weather viscosity, which means it flows easier when the temperatures are colder. This can be beneficial to have an improved engine start in cooler conditions.
0w40 has a higher viscosity in cold weather, which means it is better at protecting your engine during extreme cold or long idling times in winter months.
3. High-temperature viscosity
0w20 has a higher high-temperature viscosity, which means it is better at protecting your engine from the heat and friction of hot weather and high operating temperatures.
0w40 has a lower high-temperature viscosity, which means it flows easier and reduces internal friction and resistance in the engine.
4. Thermal stability
0w20 has higher thermal stability, which means it is less likely to degrade (thicken), thicken more slowly, or form deposits when exposed to high operating temperatures.
0w40 has lower thermal stability, which means it can degrade (thicken) and cause oil pressure loss more easily at high temperatures.
It is also more likely to form harmful deposits of metallic particles and sludge when exposed to high engine temperatures for longer periods.
0w20 has a higher pumpability, which means it is less likely than 0w40 to cause issues such as filter clogging, oil passage plugging, and decreased oil pressure.
It also flows better through the engine oil pump, which means it is being delivered to the engine in greater quantities for better lubrication.
0w40 has a lower pumpability, which means it has the potential to cause issues such as filter clogging, oil passage plugging, and decreased oil pressure.
6. Viscosity index
0w20 has a higher viscosity index, which means it has a higher resistance to viscosity breakdown when exposed to high operating temperatures.
This gives it the ability to provide better protection and performance over 0w40 when exposed to high temperatures for long periods. 0w40 has a lower viscosity index, which means it has less resistance to viscosity breakdown at high temperatures.
This means it may not provide the same level of protection or performance as 0w20 when exposed to high operating temperatures for long periods.
7. Cold weather performance
0w20 has better cold-weather performance, making it ideal for sub-zero climates where colder starting is important. It can help your engine start more easily in cooler temperatures when compared with 0w40.
0w40 has better cold-weather performance in warmer climates, where a cold startup isn’t as critical.
8. Suitable for modern engines
0w20 is suitable for use in modern gasoline engine passenger cars, including direct injection (DI) and turbocharged (T/C) models, provided the manufacturer’s technical recommendations allow it.
0w40 can also be used in modern gasoline engines, including direct injection and turbocharged cars if the owner manual allows it.
9. High-performance engines
0w20 is a high-performance oil that can provide enhanced protection when used in high-performance turbocharged gasoline engine passenger cars. 0w40 is not recommended for use in high-performance turbocharged gasoline engine passenger cars.
10. Fuel economy benefits
0w20 may provide improved fuel economy when compared with 0w40, however, this will depend on how you drive, your engine, and its normal operating temperature range. Consult your vehicle handbook to confirm the engine oil specification suitable for your vehicle.
Can 0w20 be used in an older engine?
High-mileage cars can benefit from using 0w20 motor oil because the additive package (or formula) is specifically designed to protect your engine under high stress and increased temperatures. Car manufacturers recommend adding 0w20 in their newer engines.
Can 0w20 cause harm to the older engine?
It is a common question among drivers. The thought of using a lower viscosity grade such as 0w20 or 5w20, than what is recommended by their car manufacturer, can be scary to them.
Even if the benefits of these low-weight oils might outweigh the risks that may exist with older engines, try not to add 0w20 into your engine if the manufacturer does not recommend it because it may harm the engine.
Can 0w40 be used in a newer engine?
Can 0w40 cause any harm to the engine?
0w40 can cause harm to the engine if it is used in temperatures below -20°F (-29°C) or the manufacturer doesn’t recommend adding it.
This oil has a lower viscosity than other oils, which means that it will thin out even more at colder temperatures. It also does not have as high of a viscosity index as other oils, which means that it may not perform as well in the cold.
Can you mix 0w20 and 0W40?
Mixing oil viscosities is risky, but the best choice is to mix only the same grade of oil. Using different grades can cause problems in your engine that might not be noticeable at first.
The verdict? 0w40 is the better engine oil for most vehicles. If you have a newer car or one that requires thinner oils, then using 0w20 would be the best choice. However, if your vehicle doesn’t require a specific weight of oil and you’re not sure which to choose, it’s always safest to go with 0w40.