What is the difference between 0W-20 and 5w30 oil?

When it comes to motor oil, the numbers and letters can be confusing, but they actually provide important information about the oil's viscosity and performance characteristics. The key difference between 0W-20 and 5W-30 oil lies in their viscosity ratings, which impact factors like engine protection, fuel efficiency, and cold-weather performance.

Viscosity Ratings Explained

The viscosity of motor oil is measured using the Society of Automotive Engineers (SAE) viscosity grading system. The first number, such as 0 or 5, refers to the oil's cold-weather viscosity, while the second number, such as 20 or 30, refers to the oil's hot-weather viscosity.

• 0W-20: The "0W" indicates the oil has a very low viscosity at cold temperatures, making it easier to pump and circulate through the engine during startup. The "20" means the oil has a medium viscosity when the engine is hot and running.


• 5W-30: The "5W" indicates the oil has a slightly higher viscosity at cold temperatures compared to 0W-20, but it still flows easily during startup. The "30" means the oil has a higher viscosity when the engine is hot and running.

The viscosity ratings are important because they affect how the oil behaves in different operating conditions. Lower viscosity oils like 0W-20 can improve fuel efficiency, while higher viscosity oils like 5W-30 provide better engine protection under high-load conditions.

Choosing the Right Oil for Your Vehicle

The recommended oil viscosity for your vehicle is typically specified by the manufacturer in the owner's manual. This recommendation is based on factors like the engine design, operating conditions, and climate. In general:

• 0W-20 oil: Recommended for many modern, fuel-efficient engines, especially in warmer climates. It can improve fuel economy and provide good cold-weather performance.


• 5W-30 oil: A more common and versatile choice, suitable for a wide range of engines and operating conditions. It provides a good balance of engine protection and fuel efficiency.

It's important to always use the oil type recommended by your vehicle's manufacturer to ensure proper lubrication and engine performance. Consult your owner's manual or speak with a qualified mechanic if you're unsure which oil is best for your vehicle.

Why do dealerships give you 0W20 oil?

Modern 0W20 synthetic oil delivers a perfect balance of engine protection and efficiency. Unlike conventional oils that thicken significantly in cold weather, 0W20 maintains consistent viscosity across temperature extremes.

Can I use 0W-20 in hot weather?

In fact, ENEOS fully synthetic 0W-20 motor oil is particularly well-suited for use in extreme temperatures, as it is designed to maintain excellent viscosity even in extreme cold and hot weather.

What is the gas mileage difference between 0W20 and 5W30?

0W-20 oil offers better fuel economy compared to 5W-30 due to its lower viscosity, which reduces engine drag and can result in a 0.5% to 4.5% improvement in miles per gallon. However, 5W-30 provides greater long-term engine protection, particularly under high-stress and high-temperature conditions, while 0W-20 has been linked to higher engine wear in long-term use. The correct choice depends on your vehicle's specific requirements and your driving conditions; always use the viscosity recommended in your owner's manual.
 
This video explains the difference between 0W-20 and 5W-30 oils: 55sCar Care CluesYouTube · Oct 27, 2025
0W-20: Better fuel economy 

• Reduced drag: Being a thinner oil, 0W-20 has lower viscosity, which allows engine parts to move more freely and requires less energy to pump. 
• Higher MPG: This reduction in friction can lead to improved fuel economy, with studies showing an average increase of 0.5% to 4.5%. 
• Better for cold starts: The "0W" designation indicates a lower viscosity in cold temperatures, allowing for faster oil flow and better protection during cold starts. 
• Ideal for modern engines: Newer vehicles with precise tolerances, direct injection, and variable valve timing are often designed specifically for 0W-20 oil. 

This video explains the impact of oil viscosity on fuel economy: 59sArrow GearheadYouTube · Oct 26, 2025
5W-30: Better long-term engine protection 

• Stronger film: It provides a thicker, stronger protective film between engine parts, especially under high heat and load, which is crucial for preventing wear. 
• Reduced wear: Long-term testing has shown that engines using 5W-30 experienced significantly less bearing wear and other types of wear compared to those using 0W-20. 
• Ideal for older engines: The increased thickness may offer better protection for older engines with looser tolerances. 

This video discusses how to choose the right oil for your engine: 57sCar Care CrewYouTube · Oct 22, 2025
How to choose

• Follow the owner's manual: Always use the oil viscosity recommended by your vehicle's manufacturer to ensure proper engine protection and avoid voiding your warranty. 
• Consider your climate: If you live in a very hot climate or drive under heavy load, 5W-30 may offer better high-temperature protection. If your vehicle is designed for it, 0W-20 is generally better for colder climates and everyday driving. 
• Balance efficiency and durability: 0W-20 is better for short-term efficiency gains, while 5W-30 is often better for long-term engine durability. 

What happens if you use 5W-30 instead of 0W-20?

Using 5W-30 instead of 0W-20 can cause a slight increase in engine wear over the long term due to the thicker oil, which may not be properly handled by a system designed for 0W-20. The 5W-30 oil is thicker at cold starts, which can lead to delayed oil pressure, and is 50% more viscous at high temperatures, which could impact fuel economy. However, some tests suggest that for many engines, the difference in long-term wear is statistically insignificant. 
Potential effects of using 5W-30 instead of 0W-20
Immediate effects

• Slightly slower cold starts: The "5W" (winter) means the oil is slightly thicker when cold than "0W," which could slightly delay oil pressure during very cold startups. 
• Lower oil pressure: In some engines, the thicker oil may not flow through the same clearances as the 0W-20, potentially causing the oil pump to work harder. 

Long-term effects

• Potential for increased wear: Some experts believe the thicker oil could lead to increased wear on engine components, especially if the engine was specifically designed for the thinner 0W-20 viscosity. 
• Reduced fuel economy: The thicker oil will likely result in a slight decrease in fuel efficiency compared to 0W-20. 
• Lower oil volatility: Thicker oils tend to have lower volatility, meaning they are less likely to evaporate at high temperatures. This can reduce carbon buildup on intake valves and in the catalytic converter. 
• Potential warranty issues: If your engine is under warranty, using oil that is not explicitly recommended in your owner's manual could void the warranty in case of a mechanical failure. 

Why some people switch from 0W-20 to 5W-30

• Higher mileage engines: As engines age and gain mileage, a thicker oil can help reduce oil consumption and quiet down the engine. This is because the increased viscosity can better seal worn parts. 
• Hot climates: In very hot climates, a thicker oil like 5W-30 can provide better protection at high operating temperatures. 

What to do if you're unsure

• Check your owner's manual: Always refer to your owner's manual to see what oil viscosities are recommended for your specific vehicle. 
• Consider your climate and driving style: If you live in a very cold climate or do a lot of high-speed driving, a thicker oil might be a better choice. If you live in a moderate climate or do mostly city driving, the recommended 0W-20 is likely the best option. 
• Consult a mechanic: If you're still unsure, consult with a mechanic for personalized advice.