With so many options, choosing the right motor oil can be bewildering. We cut through the confusion to help you make the best choice for your vehicle.
What Type of Oil Does My Car Need?
Updated on Feb. 24, 2025
Oil is often subject to heavy stress and high heat. Using the wrong oil can result in reduced performance, increased wear and even costly engine damage over time. But with so many options on the market, choosing the right oil for your vehicle can get confusing.
“Knowing the right oil to use for your vehicle is vital, but many people, unfortunately, choose the wrong type because they don’t understand the difference between synthetic and conventional oils or they confuse the viscosity ratings,” says Joe Giranda with CFR Classic.
Luckily, it’s not too difficult to decode what type of oil your car needs. Here’s how to figure it out, plus what else you need to know before changing your oil.
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What Is Motor Oil?
Motor oil is an engine’s lifeblood — a truly amazing substance. It pumps throughout the running engine via small passages called galleries, cleaning, lubricating, cooling and cushioning moving engine parts while holding sludge, abrasive particles and harsh chemical contaminates in suspension. Old motor oil needs to be changed periodically to keep your engine running smoothly.
Read the Labels
When reading a motor oil label, start with the viscosity rating, like 5W-30 or 10W-40. “The first number, with the ‘W’ for winter, indicates oil flow during colder temperatures, an important factor when starting an engine in the cold,” says Giranda. “The second number shows the thickness of the oil at higher operating temperatures, which is important for protecting the engine during heavy use.”
Choose the oil viscosity based on your vehicle manufacturer’s recommended rating (check your owner’s manual for that, as well as whether it requires synthetic oil). It might also be displayed on the oil cap. Also, here’s the type of winter oil your car needs to function smoothly.
Next, check for certifications like “API SN” or “ACEA A3/B4.” These certify that the oil is of good quality and meets industry standards for performance and engine protection. “If the oil is for specialized engines like turbocharged or diesel engines, also ensure that the oil meets the certifications stated in your vehicle manual,” says Giranda.
Types of Motor Oil
Conventional motor oil begins its life in the ground as crude (base) oil. It is then refined to remove impurities and blended with different chemical additives. Those additives include detergents to neutralize sludge, antioxidants that inhibit metal degradation, and anti-foam agents that prevent air bubbles. This is the least expensive type of motor oil.
High-mileage motor oil is formulated for vehicles with 75,000 miles or more on the odometer. This oil contains additives and chemical enhancers that can cause internal and external O-rings and gaskets to swell, potentially reducing oil leakage and burning in older engines. High-mileage motor oil will not fix mechanical failures or excess wear. But if your vehicle has been properly maintained and is running and performing well, high-mileage engine oil might be the right choice to extend the life of critical engine parts. It might keep your vehicle running much longer than planned.
High-mileage motor oil can be formulated from conventional, synthetic-blend or full-synthetic motor oil and will be priced similar to those types of oil.
Synthetic-blend motor oil is the best of both worlds. It is a mixture of synthetic and conventional base oils with additives found in both. It has excellent engine protection properties at a lower cost than full synthetics. Full-synthetic motor oil is ideal for vehicles that demand ultimate levels of protection. This type of motor oil is in the middle price range.
Full synthetics begin with base oil. However, extensive refining processes remove more impurities than with conventional oil. And the addition of artificially made compounds and higher performing additives help keep an engine cleaner and protect it from damage. Synthetic oil, although superior, is not recommended for all vehicles. Older model vehicles are designed to use conventional oil. Full synthetic is the most expensive type of motor oil.
Can I Mix Different Types of Oil?
Yes, but don’t. It is a waste of money. Even if you add full synthetic to conventional oil, you still end up with only the properties of a conventional oil.
“The combination won’t put you or your engine in any sort of immediate danger, but mixing oils with different composition and viscosity levels can cause your engine to run less efficiently and wear faster due to uneven lubrication,” says Duane “Doc” Watson, a technical trainer at Bosch Mobility Aftermarket.
Also, keep in mind that synthetic blends are formulated with different additives to better protect an engine against wear, high heat, cold weather, and sludge build-up, which are not found in conventional oils. So, when choosing a motor oil, consider the type of driving you do. Harsh driving conditions, such as city vs. highway, off-roading or along dusty, dirty roads, require motor oil to work harder and be changed more frequently.
Short trips of less than 15 minutes make up the most severe driving conditions. If the engine doesn’t reach the top operating temperature consistently, it can’t burn off water condensation, allowing sludge build-up to form.
Always refer to your owner’s manual to determine which motor oil is recommended to protect your vehicle. Be sure to dispose of used oil properly.
About the Experts
- Duane “Doc” Watson is a technical trainer at Bosch Mobility Aftermarket. He has more than 45 years of experience in automotive repair, has trained thousands of technicians and earned many industry awards, including Chevrolet Technician of the Year and Buick Service Master of the Year.
- Joe Giranda is Director of Sales and Marketing for CFR Classic, where he’s worked as an automotive expert for 23 years.
