Does it matter what kind of oil you put in your car?

The short answer is yes, it does matter what type of oil you use in your car. The type of oil you choose can have a significant impact on your vehicle's performance, fuel efficiency, and overall longevity. In this article, we'll explore the importance of using the right oil for your car and provide some guidance on how to make the best choice.

Understanding Engine Oil Types

Engine oils are not all created equal. They come in a variety of types, each with its own unique properties and intended use. The most common types of engine oil include:

• Conventional oil - This is the most basic type of engine oil, made from refined crude oil. It's generally the least expensive option but may not provide the same level of protection as other types.


• Synthetic oil - Synthetic oils are engineered in a laboratory to have specific properties that can improve engine performance and efficiency. They are typically more expensive than conventional oils but offer superior protection and longer-lasting performance.


• Synthetic blend oil - This is a mixture of conventional and synthetic oils, offering a balance of cost and performance.


• High-mileage oil - Designed for vehicles with over 75,000 miles, high-mileage oils contain additives that help to reduce oil consumption and prevent leaks in older engines.

The type of oil you should use in your car is typically specified by the manufacturer in your owner's manual. It's important to follow these recommendations to ensure your engine is properly lubricated and protected.

Why Oil Type Matters

Using the wrong type of oil in your car can have several negative consequences:

• Reduced fuel efficiency - Certain oil types can increase engine friction, leading to decreased fuel economy.


• Increased wear and tear - Oils that don't provide adequate lubrication can cause accelerated wear on engine components, leading to costly repairs down the line.


• Decreased performance - Low-quality or inappropriate oils may not be able to withstand the high temperatures and pressures inside your engine, resulting in reduced power and acceleration.


• Shortened engine life - Improper oil use can lead to premature engine failure, requiring a costly replacement.

To avoid these issues, it's crucial to use the oil type recommended by your vehicle's manufacturer. This information can typically be found in your owner's manual or on a sticker inside the driver's side door jamb.

Choosing the Right Oil for Your Car

When selecting an engine oil, there are a few key factors to consider:

• Viscosity - This refers to the oil's thickness or resistance to flow. The recommended viscosity is usually listed as a number, such as 5W-30 or 10W-40.


• Oil type - As discussed earlier, you'll need to choose between conventional, synthetic, or synthetic blend oil based on your vehicle's requirements.


• Mileage - If your car has over 75,000 miles, you may want to consider a high-mileage oil to help prevent leaks and reduce oil consumption.

Remember, using the wrong oil can void your vehicle's warranty, so it's always best to consult your owner's manual or speak with a trusted mechanic to ensure you're making the right choice.

What happens if I use 5W-40 instead of 5w30?

Putting 5W-40 instead of 5W-30 will result in slightly decreased fuel efficiency and potential performance issues, but is unlikely to cause major damage, especially in warmer climates or for older engines. The main difference is that 5W-40 oil is thicker at operating temperature, which can slightly increase friction and oil pressure. It's always best to follow the manufacturer's recommendation, which is found in your owner's manual or on the oil fill cap. 
What to expect

• Slightly reduced fuel economy: Thicker oil creates more drag on engine components, leading to a small decrease in fuel efficiency. 
• Potential performance impact: A thicker oil may slightly reduce high-end horsepower. 
• Increased oil pressure: 5W-40 has higher viscosity, which can lead to higher oil pressure readings. 
• Potential benefit for older engines: A thicker oil may be beneficial for older, high-mileage engines that have increased wear and tear, as it can help maintain oil pressure. 
• No harm in cold starts: The "5W" rating is the same for both oils, meaning both will have similar flow characteristics during cold starts. 

When to be cautious

• Modern engines: Modern engines are designed with precise tolerances, and using a thicker oil can cause problems that the manufacturer did not design for, so it is best to stick with the recommended 5W-30. 
• Warranty issues: Using an oil that does not meet the manufacturer's specifications can potentially void your warranty. 
• Stop-and-go traffic: If your engine runs hot in stop-and-go traffic, the thicker oil could be a benefit. 

Best practices

• Check your owner's manual: The manufacturer's recommendation is the safest guide. Check the manual for the correct oil viscosity and specifications. 
• Don't switch for "just because": There's no need to switch from 5W-30 to 5W-40 unless you have a specific reason, such as a high-mileage engine or a preference for heavier oil in a hot climate. 
• Stick to a single type: If you do switch, make sure to use the new oil at your next oil change, as mixing different viscosities is not ideal. 

Is it bad to put a different type of oil in your car?

Firstly, Mixing different brands of oil really isn't going to harm anything. What could happen is your oil life might be shorter and your oil may not perform at its best because the additive profile of each brand of oil could come together and may clash and could potential hurt the performance of the oil.

What happens if you accidentally put 10w30 instead of 5w30?

Using 10W-30 instead of 5W-30 is generally acceptable for many vehicles, especially in warmer climates or with older engines, as both oils have the same viscosity at operating temperature. However, 5W-30 is recommended for cold climates because its lower "winter" viscosity allows it to flow more easily during cold starts, reducing initial engine wear. Swapping to 10W-30 in a vehicle designed for 5W-30 can lead to slower oil flow and potential damage if it's frequently exposed to temperatures below freezing. 
When it's likely okay

• Warmer climates: If temperatures consistently stay above 0∘F0 raised to the composed with power cap F0∘𝐹 (-18∘Cnegative 18 raised to the composed with power cap C−18∘𝐶), the thicker 10W-30 is less likely to cause problems. 
• Older engines: A slightly thicker oil can sometimes help older, high-mileage engines that might burn oil or have larger internal gaps due to wear. 
• Moderate driving: If you don't frequently drive in extreme cold, the difference will be minimal. 

When to avoid it

• Cold climates: In regions where temperatures frequently drop below freezing, the 10W-30 will be thicker and may not lubricate the engine as quickly on a cold start, which is when most engine wear occurs. 
• Modern engines: Newer vehicles with specific requirements for oil pressure, like those with variable valve timing (VVT), should stick to the manufacturer's recommendation to avoid potential issues. 
• When the owner's manual specifies 5W-30: The safest and best practice is to always use the oil viscosity recommended in your vehicle's owner's manual, as it was specifically chosen for that engine's design. 

This video explains the difference between 5W-30 and 10W-30 motor oils: 53sThe Savvy ProfessorYouTube · Apr 19, 2023
Potential signs of a problem
Tougher cold starts, Ticking or tapping noises after startup, Higher than normal oil pressure reading, and A noticeable drop in fuel economy.

Will it hurt my car if I put 5W20 instead of 5w30?

Putting 5W-20 oil in a car that requires 5W-30 will likely not cause immediate damage if done temporarily, but it is not recommended and could lead to long-term issues, especially in high-stress conditions. The thinner 5W-20 oil may result in slightly reduced fuel efficiency and may not provide sufficient high-temperature protection, leading to increased engine wear over time. It is best to switch back to the manufacturer-recommended 5W-30 at the next oil change. 
Potential issues with using 5W-20 instead of 5W-30 

• Reduced high-temperature protection: The main difference is that 5W-30 is thicker at normal operating temperatures. Using 5W-20 means a thinner oil film between engine parts, which can lead to metal-to-metal contact and increased wear, particularly during hard driving, towing, or in hot climates. 
• Decreased fuel economy: Using the incorrect oil viscosity can slightly lower fuel economy because the thinner oil creates less internal engine drag. 
• Potential for engine damage: While a single instance is unlikely to cause lasting harm, the increased wear from thinner oil can lead to accelerated engine damage and potentially void your warranty if a problem arises. 

What to do

• Change the oil: If you have accidentally put 5W-20 in a car that needs 5W-30, get the oil changed to the correct 5W-30 as soon as possible. 
• Monitor your engine: Keep an eye and ear on your engine for any unusual noises, especially after it has reached operating temperature, and check for any performance changes. 
• Consult your owner's manual: Always refer to your car's owner's manual to confirm the manufacturer's specific recommendations. They may list different oil viscosities based on climate conditions.