How do I know what kind of oil I need to change?

The quick answer is to check your vehicle’s official guidance. Your owner’s manual or the engine bay label will specify the exact viscosity and specification required. For most modern cars, that means a 0W-20 or 5W-30 oil that meets API SP and ILSAC GF-6 standards, and may require OEM approvals such as Dexos, VW 502.00, or MB 229.x.

Where to find the right specification

To confirm the exact oil your engine needs, rely on these sources. They are the most reliable starting points and help protect warranty coverage and engine performance:

1. Owner’s manual or the manufacturer’s online model page, which lists approved viscosities and oil specifications.


2. Under-hood oil fill cap or a sticker in the engine bay showing the recommended grade and required spec.


3. Service interval stickers or maintenance booklet from the dealer or service center.


4. Manufacturer’s official website or a VIN-based lookup tool for your exact build and variant.


5. Ask a dealership service advisor or a trusted mechanic if you’re unsure after checking the manual and labels.

Relying on these sources ensures you use the correct oil for your engine’s design, which can affect performance, emissions, and warranty coverage.

Understanding the oil numbers and specs

Before buying oil, it helps to understand what the labels actually mean. The following points cover the most common questions.

What the oil labels tell you:

• Viscosity grade: The two numbers separated by a W indicate cold-temperature flow (first number) and high-temperature thickness (second number). For example, 0W-20 flows well in cold weather and is light at operating temperature, while 5W-30 is slightly thicker but still suitable for many engines. Always match the grade to what your manual specifies.


• Performance and approval standards: API (such as SP or SN Plus) and ILSAC (GF-6) designations show the oil’s overall performance in gasoline engines. Some vehicles require OEM-specific approvals (for example Dexos1 Gen 2 for many GM engines, VW 502.00 for certain VW/Audi engines, or MB 229.x for Mercedes-Benz engines).


• Synthetic vs. conventional: Some engines require full synthetic or synthetic-blend oil for optimum protection and performance, especially turbocharged, high-stress, or longer-drain scenarios. The manual will state whether conventional oil is acceptable or if synthetic is recommended.

Ultimately, the correct oil is the one that matches both the viscosity and all the specification requirements listed by the manufacturer.

Vehicle types and their oil needs

Gasoline and diesel passenger cars

Most modern cars fall into one of these categories. Use the precise viscosity and OEM/spec approvals called out by the manufacturer. If your vehicle is European, Japanese, or American with a modern engine, it’s common to see 0W-20, 0W-30, or 5W-30 as the base viscosity, with API SP/ILSAC GF-6 and OEM approvals such as Dexos1 Gen 2 or VW 502.00.

Guidance for this category:

• Follow the manual’s viscosity and specification exactly; do not substitute a different spec to “save money” or run a longer interval.


• Check for additional OEM approvals (Dexos, VW, MB, BMW, etc.) if your VIN or model requires them.


• Consider climate and driving style when choosing between 0W-20/0W-30 and 5W-30/5W-40; colder climates favor lower first numbers for easier starts, while hotter climates may tolerate higher second numbers for protection.

Conclusion: The safest route is to mirror the exact spec and grade listed for your specific model and engine variant.

Motorcycles and performance bikes

Motorcycles often require oils with different standards (such as JASO MA or MB) and may call for different viscosities than cars. Always consult the bike’s owner or service manual.

Key considerations:

• Follow the motorcycle-specific oil specification (for example, JASO MA/MB) and the recommended viscosity range for your engine and climate.


• Wet-clutch motorcycles may require oils with properties that prevent clutch slip; car engine oils won’t always be suitable.


• Some bikes demand synthetic or semi-synthetic oils to withstand higher operating temperatures and rpm ranges.

Conclusion: Do not use car engine oil in motorcycles unless the manual explicitly allows it. Always use motorcycle-grade oil with the correct spec.

Hybrid and high-mileage engines

Hybrid powertrains and older, high-mileage engines can have specialized needs. The manufacturer may require specific low-viscosity oils to optimize efficiency or special formulations to minimize leaks and wear.

• Check if the hybrid requires a unique grade or an engine oil that supports dual powertrains or micro-hybrid systems.


• High-mileage oils can include additives to protect worn seals or reduce oil consumption, but they must still meet the OEM spec.


• Even in hybrids, the oil spec (API/ILSAC and OEM approvals) remains the governing factor.

Conclusion: Always verify with the manual or dealer for any model-specific exceptions or updates to the recommended oil.

How to verify before you change the oil

Before draining and refilling, follow these checks to ensure you choose the correct oil and avoid unnecessary trips to the shop:

1. Locate the exact oil specification in the owner's manual or the manufacturer’s online resources.


2. Inspect the oil fill cap and any under-hood labels for the required viscosity and approvals.


3. Consider your climate and driving patterns (short trips, lots of stop-and-go, towing) which can influence the best viscosity and drain interval.


4. Decide between conventional, synthetic-blend, or full synthetic oil based on engine design, warranty, and your driving demands.


5. If you’re unsure, consult a dealership or qualified technician to confirm the correct oil for your engine.

Conclusion: Accuracy matters for engine protection and warranty; when in doubt, seek professional guidance and double-check the latest specification for your model.

Summary

To know what oil your car needs, start with the official guidance in your owner’s manual or engine bay labels, and verify any OEM approvals required by your model. Understand the two-part viscosity (the W-rated cold flow and the high-temperature number) and the performance specs (API, ILSAC GF-6, and OEM approvals). Different vehicle types—cars, motorcycles, hybrids—have their own specific requirements, so use the exact spec for your engine. When in doubt, consult the dealer or a trusted technician to ensure you protect your engine today and in the long term.

How do I know if my car takes synthetic oil or regular oil?

The easiest way to tell if oil is synthetic or conventional is to check the bottle's label for terms like "synthetic," "full synthetic," or "synthetic blend," as these labels are legally required to indicate the oil's type. You can also check the car's owner's manual to see if synthetic oil is recommended or required, as this is the best way to know what type of oil your vehicle needs. Other methods, like looking at the oil's color or consistency, are unreliable. 
On the bottle

• Look for explicit text like "synthetic," "full synthetic," or "synthetic blend" on the front label. 
• Check the API (American Petroleum Institute) "donut" symbol on the back. While it doesn't always explicitly state "synthetic," the recommended specifications and certifications printed on the label are the most important indicators, as seen in Pennzoil® and this YouTube video. 

This video explains how to identify synthetic oil based on its properties and certifications: 58sCRP AutomotiveYouTube · Jul 31, 2019
In your car's owner's manual

• Consult the manual to find the manufacturer's specific oil recommendation.
• The manual will list the required oil type (e.g., full synthetic, synthetic blend, or conventional) and the correct viscosity grade (e.g., 5W-20). 
• Using the oil type specified in the manual is the most crucial step in maintaining your engine, regardless of other factors. 

Unreliable methods

• Color: Both conventional and synthetic oils can vary in color and darken over time as they collect grime. 
• Consistency and feel: It is difficult and unreliable to determine the type of oil by feel, especially after it has been in the engine. 
• Microscope: While conventional oil molecules are irregular and synthetic oil molecules are more uniform, this is only visible under a microscope and not a practical way to check your oil. 

You can watch this video to see a simplified comparison of molecular structures between synthetic and conventional oils: 1mEngineering ExplainedYouTube · Dec 16, 2020

How do I know what kind of oil change I need?

You need the specific oil type and viscosity (e.g., 5W−305 cap W minus 305𝑊−30 synthetic) recommended by your vehicle's manufacturer, which you can find in the owner's manual or by using an online oil selector tool from a brand like Pennzoil. Key factors for choosing are the car's manual, engine age and mileage, climate, and your driving habits. 
Determine the correct oil

• Check your owner's manual: This is the most important step, as it lists the manufacturer's specifications for oil grade and viscosity, such as 5W−305 cap W minus 305𝑊−30. 
• Use an online oil selector: Many oil brands have tools on their websites where you can enter your vehicle's year, make, and model to find the recommended oil. 
• Look up your vehicle's information: Websites from service centers like Firestone and retailers like Walmart can help you find the right oil. 

Choose the right type of oil

• Conventional Oil: An affordable option, often suitable for older vehicles without special requirements. It may need to be changed more frequently than synthetic. 
• Synthetic Blend: A mix of conventional and synthetic oils that offers better performance and protection than conventional alone. 
• Full Synthetic: Offers the best performance, protection, and longevity. It is ideal for modern cars, high-performance vehicles, and those driven in extreme temperatures or with severe conditions like frequent short trips. 
• High Mileage: Specially formulated for vehicles over 75,000 miles to help reduce oil burn-off and leaks. 

Consider your driving conditions

• Climate: A thinner oil (lower "W" number) is better for cold climates, while a thicker oil (higher second number) provides more protection in high heat. 
• Driving habits: If you have severe conditions like short trips (under 5 miles), towing, or stop-and-go traffic, you may benefit from synthetic oil, and you should change it more often, according to your manual. 

What are signs that synthetic oil needs changing?

Signs You Need An Oil Change

• Engine Knocking Noises. One of the most common symptoms of overdue oil change is a knocking or ticking noise coming from your engine.
• Increased Engine Heat.
• Reduced Fuel Efficiency.
• Dark, Dirty Oil.
• Check Engine Light.
• Decreased Performance.
• Smoke from the Exhaust.
• Unusual Smells.

What happens if I put 5W-30 instead of 5W-20?

Putting 5W-30 in an engine that calls for 5W-20 is generally not a major issue for short-term use, but it can lead to slightly reduced fuel efficiency and may affect variable valve timing systems. Over time, the thicker oil may cause slightly more wear, so it's best to switch back to the recommended 5W-20 at your next oil change. 
Effects of using 5W-30 instead of 5W-20

• Slightly lower fuel economy: 5W-30 is thicker at operating temperature, so the engine has to work slightly harder to pump it, which can lead to a small reduction in gas mileage. 
• Impact on variable systems: Modern engines with variable valve timing (VVT) or similar systems rely on specific oil viscosity for proper function. A thicker oil can alter the system's pressure and performance, though this is often a minor effect. 
• Increased engine pressure: The increased thickness can lead to a slightly higher pressure inside the engine. 
• Potential for minor wear: While the extra wear is very slight and unlikely to cause immediate damage, it's a consideration for long-term use, as the engine was designed for the thinner 5W-20 oil. 

What to do

• Don't panic: Driving with 5W-30 for a short period will not cause immediate, significant damage to most engines. 
• Change to the correct oil: At your next opportunity, get an oil change and replace the 5W-30 with the manufacturer's recommended 5W-20 oil. 
• Monitor your engine: Listen for any unusual noises and check for any changes in performance as you continue to drive. 
• Check the owner's manual: Always refer to your vehicle's owner's manual for the specific oil viscosity recommended for your engine, as it's the most reliable source of information.