Engine oil weight refers to the viscosity of the oil, which measures its resistance to flow. The oil’s viscosity is represented using a multigrade rating system, such as 5W-30 or 10W-40. This rating tells you how the oil behaves at low and high temperatures.
In this guide, we’ll break down engine oil weight classifications, their meaning, and how they impact engine performance. We will also provide a detailed engine oil weight chart in a tabular format for easy reference.
Engine Oil Weight Chart
| Oil Weight | Cold Weather Performance | Hot Weather Performance | Best Used For |
|---|---|---|---|
| 0W-20 | Excellent for extreme cold (flows easily) | Thinner at high temperatures | Newer vehicles, hybrid engines, fuel-efficient cars |
| 0W-30 | Excellent for cold climates | Better protection in high heat than 0W-20 | High-performance engines, cold regions |
| 5W-20 | Good for moderately cold temperatures | Low viscosity at high temps | Modern fuel-efficient engines, hybrid cars |
| 5W-30 | Good for cold starts | Moderate viscosity at high temps | Most passenger cars, light trucks |
| 10W-30 | Fair cold-start performance | Stable at high temperatures | Older vehicles, mild climates |
| 10W-40 | Thicker at high temps, moderate cold flow | Extra protection at high heat | Heavy-duty engines, high-mileage vehicles |
| 15W-40 | Limited cold-weather flow | Excellent protection in heat | Diesel engines, heavy trucks, industrial vehicles |
| 20W-50 | Poor cold-weather performance | Extremely thick at high temps | Racing engines, older vehicles, extreme heat conditions |
Read Engine Oil Specification Chart(A to Z Guide)
Why Is Engine Oil Weight Important?
- The correct oil weight:
- Ensures proper lubrication and reduces friction.
- Enhances fuel efficiency and engine performance.
- Prevents wear and tear by forming a protective layer on engine components.
- Protects the engine under extreme temperatures (both hot and cold).
How to Choose Right Engine Oil Weight for Your Vehicle
1. Consider Your Climate
- If you live in cold climates, choose a lower first number (e.g., 0W or 5W) for easier cold starts.
- If you live in hot climates, select oil with a higher second number (e.g., 40 or 50) for better heat protection.
2. Follow the Manufacturer’s Recommendations
Always check your vehicle’s owner’s manual for the recommended oil weight. Car manufacturers test their engines to determine the ideal viscosity for optimal performance and longevity.
Read Engine Oil Thickness Chart(A to Z Guide)
3. Consider Your Driving Habits
- Short city trips: Use a lower viscosity oil like 0W-20 or 5W-30 for better fuel economy.
- Long highway drives or towing: Opt for a higher viscosity oil like 10W-40 or 15W-40 to withstand engine stress.
FAQ
Can I use 30 weight oil instead of 10W-30?
Using 30-weight oil (SAE 30) instead of 10W-30 depends on your engine type and climate. SAE 30 is a single-grade oil, meaning it does not provide good cold-start performance. 10W-30 is a multigrade oil, designed to flow better at cold temperatures while maintaining thickness at high temperatures.
If your engine requires 10W-30, using SAE 30 could lead to difficult cold starts and reduced lubrication in colder conditions. However, in warm climates, SAE 30 may work in older engines that don’t require multi-viscosity oil.
Read Kubota Engine Oil Capacity Chart(Models A to Z)
What happens if I put 5W-20 instead of 5W-30?
If you use 5W-20 instead of 5W-30, the oil will be thinner at operating temperature, which may lead to:
- Reduced engine protection, especially in high heat and under heavy loads.
- Slightly better fuel economy, as thinner oil reduces friction.
- Increased wear over time if the manufacturer recommends 5W-30.
Most modern engines can tolerate a slight change in viscosity, but it’s always best to follow your manufacturer’s recommendations to avoid premature engine wear.
Is 5W or 10W better for summer?
For summer, 10W-30 can be a better choice than 5W-30 if you live in a hot climate and your vehicle manufacturer allows it. The first number (5W or 10W) refers to cold-start viscosity, so it’s more relevant in winter.
The second number (30, 40, etc.) is what matters in hot weather. In extreme heat, 10W-30 or 10W-40 provides better high-temperature protection compared to 5W-30.
Read Kohler Engine Oil Chart(A to Z Guide)
What happens if I put 10W-40 instead of 5W-30?
Using 10W-40 instead of 5W-30 means the oil is thicker at operating temperature, which could cause:
- Increased oil pressure, may lead to reduced flow in tight engine clearances.
- Higher resistance to heat, which can be good in hot climates but bad for fuel economy.
- Slower lubrication on cold starts, as 10W-40 is thicker when cold compared to 5W-30.
If your engine is designed for 5W-30, switching to 10W-40 may not be recommended unless your engine is old, has high mileage, or operates in extremely hot conditions.
Will thicker oil increase oil pressure?
Yes, using a thicker oil (higher viscosity number) can increase oil pressure, as the oil moves more slowly through the engine. However, this does not always mean better lubrication.
If the oil is too thick, it may not flow properly to all parts of the engine, leading to poor lubrication and potential engine wear. Always use the recommended viscosity for your engine.
Read Car Engine Oil Color Chart(Color That Signals Immediate Danger)
Is 5W-30 or 10W-30 better for high mileage?
For high-mileage engines, 10W-30 can be a better option in hot climates as it provides slightly thicker lubrication at startup. However, 5W-30 remains the better all-around choice for most vehicles because:
- It provides better cold-start performance.
- It ensures better fuel efficiency.
- Many high-mileage oils in 5W-30 include additives that help reduce leaks and wear.
Is 5W-20 or 5W-30 better for high mileage?
For high-mileage engines, 5W-30 is generally better than 5W-20 because it offers thicker protection at operating temperatures. Older engines tend to develop larger internal gaps due to wear, and a slightly thicker oil like 5W-30 can help reduce oil consumption and leaks.
At what mileage should you use thicker oil?
Many experts suggest considering a thicker oil (higher second number) once an engine reaches 100,000 to 150,000 miles, especially if you notice:
- Oil burning or consumption (needing to add oil between changes).
- Lower oil pressure due to worn engine components.
- Increased engine noise, which thicker oil can help dampen.
However, not all high-mileage engines need thicker oil. Some modern engines are designed to run on low-viscosity oil their entire life. Always check your owner’s manual before making a change.
Read Can You Mix Different Weights of Oil(Hack or a Disaster)
Can I mix 10W-30 with 5W-30?
Yes, you can mix 10W-30 and 5W-30, as they have the same high-temperature viscosity (30). The only difference is their cold-start performance (5W-30 flows better in cold temperatures than 10W-30). Mixing them won’t harm your engine, but it’s best to stick to one oil type for consistent performance.
Is 5W-20 better than 5W-30 in hot weather?
No, 5W-30 is better than 5W-20 in hot weather because it is thicker at operating temperature, providing better protection in high heat. 5W-20 is thinner, which may lead to increased engine wear in extreme temperatures. If you drive in a hot climate or tow heavy loads, stick to 5W-30 or even 10W-30 if recommended by your manufacturer.
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Final Thoughts
Selecting the right oil viscosity is essential for engine health and longevity. Always follow your vehicle manufacturer’s recommendations and consider climate, mileage, and driving conditions before making a switch.
