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Motor oil is shown being poured into a car during a Honda oil change.

How to Choose the Right Motor Oil

The next time you stop by the dealership for your oil change, consider this: not all motor oil is created equal. While your vehicle’s manufacturer will recommend a specific type of oil based on your make and model, the choice is ultimately up to each individual driver. For example, while Honda recommends that drivers use Honda Genuine motor oil––which is sold at Honda dealers––the automaker has also given the green light for drivers to use non-Honda-branded motor oil for their Honda oil change as long as it meets the viscosity grade specified in the owner’s manual. This really expands drivers’ options, allowing them to choose a specific type of motor oil based on their budget, service schedule, and other factors.

Conventional motor oil has been the industry’s go-to for decades, but advances in oil technology have made full synthetic oil an increasingly popular option in recent years. Then there’s synthetic blend motor oil, which splits the difference between the two types, offering a well-rounded option for drivers seeking a middle ground. Lastly, high-mileage motor oil is specially formulated for vehicles that have been around the block a few times, offering superior protection for a slight premium.

Let’s take a closer look at each type of motor oil to see which one you should choose and examine how a vehicle’s mileage, usage, and age can affect the decision. To be clear, we’re not talking about the viscosity grades or “weights” of different oils, but simply the four major types of motor oil.

Conventional Motor Oil

Conventional motor oil has been around since the time of the dinosaurs. That might be an exaggeration, although the petroleum products we use in our vehicles can be traced back to decayed plant and animal matter from the Jurassic and Cretaceous periods. Conventional motor oil starts off as basic crude oil before it’s refined, filtered, and mixed with a variety of chemical additives, including detergents to combat engine sludge, antioxidants to prevent metal degradation, and other ingredients that further enhance its lubricating properties. Each brand of motor oil offers its own specific blend of additives, so the decision often comes down to which properties a driver is looking to emphasize.

Conventional motor oil’s biggest advantage comes down to its price, which can be as little as half that of full synthetic or synthetic blend motor oil. This might make conventional motor oil seem like the clear frontrunner, but it comes with one major caveat: it simply doesn’t last as long. Experts recommend changing out conventional motor oil every 5,000 miles, which is significantly more often than the recommended interval for many full synthetic options. Conventional motor oil tends to lose its viscosity over time as regular operation causes the oil molecules to break down. It may also offer poorer fuel economy than some synthetic options and accelerate wear-and-tear on the engine. These properties aren’t necessarily dealbreakers, but while conventional motor oil is a fine choice for simpler engines with low mileage that see a moderate amount of use, it’s a less viable option for some higher-mileage vehicles or those with particularly finicky powertrains.

Motor oil is shown flowing through an engine.

Full Synthetic Motor Oil

Full synthetic motor oil represents the latest and greatest in automotive lubrication technology and presents a longer-lasting alternative to conventional options. Unlike conventional oil, synthetic oil is made from chemical compounds synthesized entirely in a lab. This means that there are no impurities in the oil, and every molecule serves a purpose. Synthetic oil is also made with a premium blend of additives, which outperforms those found in conventional motor oil when it comes to lubrication, corrosion resistance, and other properties.

This high-tech manufacturing process results in motor oil that has several notable advantages over its conventional counterpart. First off, synthetic motor oil can have a lower viscosity than conventional blends. The lower viscosity, the easier the motor oil can move through the engine, lubricating vital components and keeping your vehicle’s fuel efficiency at its best. Synthetic motor oil is also better able to withstand a wide range of temperatures, meaning it will perform just as well in the dog days of summer as it will on the frostiest January morning.

Synthetic oil is also less prone to breaking down on the molecular level than conventional motor oil, which goes a long way in reducing the accumulation of power-sapping sludge while increasing the length of time between oil changes. Lastly, synthetic motor oil can sustain higher loads for longer periods than conventional motor oil, reducing wear and tear and possibly even preventing malfunctions such as low-speed pre-ignition (LSPI) on turbocharged engines. LSPI occurs when small amounts of fuel and oil leak out near the top of the piston during the compression stroke, which, when heated, could ignite and force the piston backward at the wrong time causing noticeable damage.

With all the advantages inherent to full synthetic oil, it begs the question: why would drivers ever opt for anything else? Aside from its higher cost, this normally comes down to the vehicle’s age. Synthetic motor oil is a good choice for newer high-efficiency and high-performance engines––and is paramount in any turbocharged setup––but it’s not always a great choice for older vehicles. This is due to its lower viscosity and the fact that as a vehicle ages, this low-viscosity oil can start to leak through small gaps that begin to develop through normal wear. If your older vehicle is regularly leaving oil stains on the driveway, it may be time to consider switching over to a conventional option.

Synthetic Blend Motor Oil

Synthetic blend oil splits the difference between conventional and full synthetic offerings, blending the two to produce a happy medium that works across a range of applications. It offers increased fuel economy, sludge-reduction, and high-temperature performance over conventional oil, though not quite as good as the more expensive full synthetic. Synthetic blend motor oil can have a higher viscosity than conventional motor oil and is better suited for vehicles that regularly experience heavy-duty use.

For many drivers, synthetic blend motor oil presents a more affordable alternative to full synthetic products, although some have doubts about its value. Why? Well, since there aren’t standards dictating what is and is not a synthetic blend, brands are free to mix up any concoction they like and slap a “synthetic blend” label onto it. While the best synthetic blends contain a high ratio of full synthetic to conventional motor oil, some let the balance fall as far as 20 percent synthetic to 80 percent conventional. Brands tend to keep their specific formulas private, making it difficult to know exactly what you’re getting when you invest in a synthetic blend. This isn’t to say that synthetic blends don’t generally outperform conventional motor oils, just that they can vary drastically between brands.

Motor oil is shown flowing out of a bottle.

High Mileage Motor Oil

As a vehicle ages, its needs become different, especially when it comes to motor oil. Parts start to wear down and gunk up, requiring more lubrication as the engine struggles to achieve the performance it once did. Older vehicles also have a reputation for leaking and burning oil, which can expose the engine to premature degradation and necessitate more frequent oil changes.

That’s where high-mileage motor oil comes in. Concocted using a special blend of additives and conditioners, high-mileage motor oil is ideal for older vehicles, thanks to its ability to slow or even eliminate leaks by increasing the flexibility of engine seals. High-mileage motor oil contains chemicals that can actually allow the internal and external O-rings and gaskets to expand, reinforcing compromised seals. While it’s not a substitute for regular maintenance, it can also go a long way in removing sludge and reducing burn-off-related oil loss. It can also improve fuel efficiency and reduce wear and tear, breathing new life into old, worn-out components and adding years to an aging vehicle.

Recommended for vehicles with 75,000 miles and up, high-mileage motor oil is sold in conventional, full synthetic, and synthetic blend formulations. When it comes to recommending oil change intervals for high-mileage blends, it’s tough to make a generalization as so much depends on the vehicle, its age, and many other factors. Generally speaking, older vehicles require more frequent oil changes, especially if they’re leaking or burning oil.

Pay Attention to Oil Changes!

Next time you pull into the service bay of your local mechanic or dealership, you might think twice before automatically agreeing to whatever option the mechanic suggests. While you should always try to stick fairly close to a manufacturer’s recommendation on what type of oil to use, especially when it comes to the viscosity grade, there’s typically a little more wiggle room when it comes to the type of motor oil. If you’re looking to save money, conventional motor oil offers a great bargain, but those with higher mileage or high-performance vehicles might want to explore some alternative options. Full synthetic motor oil is a great choice for those looking to protect their engines through heavy-duty use or extreme temperatures, but it’s typically not the most affordable option. Regardless of which type of motor oil you choose, sticking to a regular service schedule is vital, so make sure you keep track of when your last oil change was performed and what type of oil was used so that you’ll know when it’s time to schedule your next appointment.