Can I use 10W-30 instead of 5w20?

Generally, you should not substitute 10W-30 for a vehicle that specifies 5W-20. Use the oil viscosity recommended by the manufacturer, and consult your owner's manual or a dealer if you’re unsure. In some older engines or extreme conditions, there may be limited circumstances where a different viscosity is acceptable, but this is not universal.

What the numbers mean

The two numbers in a multigrade oil indicate viscosity characteristics at different temperatures. The first number followed by a W (for winter) describes cold-start viscosity: lower numbers mean the oil flows more easily at startup, helping protection during cold starts. The second number indicates viscosity at engine operating temperature (roughly 100°C): higher numbers mean a thicker oil when hot. Therefore, 5W-20 is thinner than 10W-30 both when starting the engine and when it’s hot, which is why manufacturers choose specific grades to balance protection, efficiency, and emissions.

When it might be acceptable

When a vehicle’s manual or a dealer explicitly allows a broader viscosity range, or in certain long-standing, older engines with looser tolerances, a higher-viscosity oil may be used under specific conditions. The following scenarios are sometimes cited by manufacturers or service bulletins:

• Older engines with higher mileage or worn tolerances that tolerate thicker oil.


• Extremely hot climates where a slightly thicker oil helps maintain film strength.


• Vehicles that explicitly list a broader acceptable range in the owner’s manual or official service guidance (for example, allowing a shift from 5W-20 to 10W-30 under severe service).


• Short-term or emergency situations where the preferred grade is unavailable, and the manual permits a temporary substitution.

Before proceeding, verify any allowances in the official documentation or with a dealership. Deviating from the recommended grade can affect warranty coverage and long-term performance.

Potential risks of using 10W-30 in place of 5W-20

Switching to a thicker oil can have several effects on a modern engine designed for low-viscosity oil. The following points summarize common concerns:

• Reduced startup protection in cold weather due to slower oil flow at low temperatures.


• Greater internal friction and slightly lower fuel efficiency in some engines due to higher viscosity.


• Potential for higher oil pressure readings, which can stress seals or sensors in some systems.


• Possible insufficient lubrication if the oil pump and passages aren’t designed for the thicker oil under certain operating conditions.


• Impact on emissions systems and variable valve timing that rely on precise oil flow characteristics.


• Warranty implications if the manufacturer requires the exact specified grade.

In practice, the most pronounced risks occur in engines designed with tight tolerances and strict oil-flow requirements. Always weigh these factors against your climate and driving habits, and rely on the manufacturer’s guidance.

What to do if you’re unsure or have already switched

If you’re uncertain or have accidentally used 10W-30 where 5W-20 is recommended, consider the following steps:

• Consult the owner’s manual or contact the vehicle manufacturer or a dealership to confirm acceptable viscosities for your model.


• If advised, switch back to the recommended grade at the next oil change and don’t extend intervals unnecessarily.


• Monitor for any unusual symptoms such as rough startup noises, oil pressure warnings, or changes in idle behavior.


• Ensure the oil meets the correct API/ILSAC specifications and the vehicle’s OEM approvals in addition to the viscosity.


• If the car is under warranty, be aware that using a non-specified viscosity can affect coverage; document advice from the manufacturer if you switch.

When in doubt, err on the side of using the viscosity specified by the manufacturer. A quick consultation with a trusted mechanic can prevent longer-term engine wear or warranty issues.

Practical tips

Keep these best practices in mind to protect your engine’s health and efficiency:

• Always follow the viscosity grade specified in your owner's manual or by the manufacturer.


• Choose oils that meet the exact OEM specification and quality standards (API/ILSAC/ACEA as applicable).


• Consider climate and driving patterns when discussing oil choices with a technician—extreme heat or cold can influence oil selection.


• If you need to top up between changes, use the same viscosity grade as specified; avoid mixing different viscosities unless the manual allows it.

Bottom line: 5W-20 is chosen for a reason in many modern engines. Use 10W-30 only if the manufacturer explicitly allows it for your vehicle and climate, and consult a professional if you’re unsure.

Summary

For most vehicles, 10W-30 is not a drop-in substitute for 5W-20 and can affect fuel economy, lubrication, and warranty coverage. The safe approach is to use the exact viscosity recommended by the manufacturer and only consider other options if official guidance confirms they are acceptable for your engine and climate. When in doubt, consult your dealer or a trusted mechanic before proceeding.

What oil can I substitute for 5W20?

5w20 and 5w30 is interchangeable, meaning you can use 5w20 in an engine that recommends 5w30, and you can use 5w30 in an engine that recommends 5w20. It's not a big deal. As long as your not making a dramatic jump from 0w20 to 20w50, you'll be fine. What really matters is your oil change interval.

What happens if you put 10W oil instead of 5W?

A common question is whether it's safe to use 10W-30 instead of 5W-30 oil, for example. While it's best to use what's recommended in your owner's manual, inadvertently using a viscosity one grade higher or lower than what's recommended generally poses no long-term harm.

Is 5W20 or 10W30 better for high mileage?

For a high mileage engine, a 10W-30 high mileage oil is often a better choice than 5W-20, as its higher viscosity can provide better protection against wear and help reduce oil consumption in engines with increased internal clearances. However, always check your vehicle's owner's manual to confirm the manufacturer's recommended oil viscosity, as some modern engines are specifically designed for 5W-20 and switching could negatively impact performance or void the warranty. 
You can watch this video to learn about the differences between 5W-20 and 5W-30 motor oils: 58sMotor MatchupsYouTube · Jan 15, 2024
10W-30 High Mileage Oil

• Better for older engines: A thicker oil can help compensate for increased engine component wear, creating a more protective film. 
• Reduces oil consumption: The higher viscosity can lead to less oil leaking or burning in engines with more wear. 
• Enhanced protection: It provides better protection under high-stress conditions and in hot temperatures. 

5W-20 High Mileage Oil 

• Better fuel economy: Its lower viscosity allows it to flow more easily, which can result in slightly better gas mileage. 
• Good for cold starts: The '5W' rating indicates it's thinner than 10W-30 in cold temperatures, aiding in cold starts. 
• Potential for less protection: While beneficial for modern, tighter-tolerance engines, it may not provide adequate protection for the increased clearances in older, high-mileage engines, especially under load. 

How to choose

1. Check the owner's manual: This is the most important step to determine the manufacturer's specified oil viscosity. 
2. Consider your engine's condition: If your engine is older with known oil consumption or pressure issues, the higher viscosity of 10W-30 is likely the better choice for protection. 
3. Consider your climate: In very hot climates or if you frequently tow, the extra high-temperature protection of 10W-30 is beneficial. 
4. Factor in fuel economy: If your main concern is maximum fuel economy and your manual specifies 5W-20, you might consider sticking with that, but be aware of the potential trade-off in long-term wear protection. 

This video explains the differences between 5W30 and 10W30 motor oils: 57sAuto V Fix YouTube · May 24, 2023

What happens if I put 10W30 instead of 5W20?

Putting 10W-30 oil in a car that calls for 5W-20 will make the oil thicker, especially at cold temperatures, which could lead to increased engine wear during cold starts and potentially lower fuel economy. In many modern engines, using the wrong viscosity can also cause issues with variable valve timing and other systems. For best practice, always use the manufacturer's recommended oil viscosity to ensure proper lubrication and fuel efficiency. 
What to expect

• Cold starts: The "10W" in 10W-30 means the oil is thicker when cold than 5W-20. This can cause increased wear when you start your engine on a cold day because it takes longer for the thicker oil to circulate and lubricate engine parts. 
• Operating temperature: At normal engine operating temperatures, the viscosity of 10W-30 and 5W-20 is similar (indicated by the "30" and "20"). 
• Fuel economy: Using a thicker oil like 10W-30 can lead to a slight decrease in fuel economy because it requires more energy to pump. 
• Engine systems: Some modern engines have variable valve timing (VVT) systems that are calibrated for a specific oil viscosity. Using a thicker oil can interfere with the operation of these systems. 

What to do

• Check the owner's manual: It is always best to follow the manufacturer's recommendation, which is found in your car's owner's manual. 
• Change the oil: For your next oil change, switch back to the correct 5W-20 oil to ensure your engine receives the proper lubrication and protection it was designed for. 
• Consider your climate: The negative effects are more pronounced in colder climates where the engine's first start is frequently at low temperatures.