What kind of oil does my car take? What does motor oil do?

What kind of oil does my car take? 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. 

Oil and filter changes are part of your routine maintenance schedule. It’s a service that’s among the easiest to do, even for a budding DIYer. And while it’s a simple procedure, few things are as crucial as using the right oil in the engine. Options abound including different viscosities and a range of oil types, and making the wrong choice could result in sudden and expensive repairs.

Engine oil prices range from around $4 per quart to $20 or more per quart, and your engine could take anywhere from four to eight quarts in most cases. But more important than the cost of changing the oil in your car is ensuring you have the right oil to protect the engine. Here’s what you need to know about choosing the right motor oil.

What does motor oil do?

What kind of oil does my car take

Knowing what roles motor oil plays in your engine’s health can help to understand why choosing the right oil is so important. Oil is first and foremost recognized as a lubricant, keeping parts separated by a thin film of molecules that act like tiny ball bearings, preventing them from rubbing against each other. Not only is it a lubricant, but engine oil also:

  • Coats metal parts to prevent rust and oxidization
  • Reduces friction between moving parts
  • Dissolves and washes away deposits and sludge from inside the crankcase
  • Circulates hot oil to the engine oil cooler to maintain the right operating temperature
  • Neutralizes acids created from the combustion process

If the wrong grade of oil is used, these protective qualities can be compromised.

Find the correct oil grade

The Society of Automotive Engineers, or SAE, has developed a grading system for engine oil. One common grade is 5W-30 engine oil, and it can be generally explained for how it performs based on its grading.

The first part of the number, 5W, indicates how well it pours in cold weather since the W stands for Winter. The lower the number, the better it flows in the cold. The second part of the number – in this case, the number 30 – indicates the oil weight at normal operating temperature. The higher this number, the thicker it is when it’s warm.

The grade you’re looking for will be marked on your engine oil cap, in most cases. You’ll also find it in your vehicle’s routine maintenance guide booklet or online. If your manual gives two different possible grades, the one with the lower numbers is intended for winter driving. For example, a car might use 5W-20 engine oil in the summer but have 0W-20 oil recommended for winter.

What kind of oil does my car take?

Grade is only one portion of the motor oil equation. Perhaps even more important is the type of oil you use in the engine. And if you’re wondering, “Are all engine oils the same?”, no they are not. It’s true that they may all start with a base oil that’s refined from crude oil drawn from the ground, but there are some very distinct differences between oil types, even though you can’t see them with the naked eye.

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What kind of oil does my car take

Conventional oil

Crude oil extracted from the earth in a variety of ways needs to be refined before it can be used in an engine. Once impurities have been removed, it’s mixed with detergents and additives that are intended to keep your engine clean and protected.

Once conventional oil has been put into the engine and used, it begins to degrade. Within a matter of months or a few thousand miles, it will be saturated by contaminants and particles that would otherwise damage the engine, and it begins to lose its protective qualities. That’s why oil changes are so important – it removes these harmful compounds from the engine for disposal.

High-mileage 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 oil

Contrary to popular belief, synthetic oil is not completely synthesized. It’s formulated from crude oil, just like conventional oil is. However, the refining process is more thorough. Synthetic oil’s molecules are a more consistent size, allowing for better protection against wear inside the engine. It’s a higher quality base oil to start with, and that means it’s more chemically stable, resists oxidization better, and won’t lose its protective properties as soon.

Combined with a better base oil, synthetic engine oil also tends to have premium additives and detergents mixed in it. Because of that, synthetic oil keeps the engine cleaner, experiences less wear, works to protect at higher temperatures better than conventional oil, and doesn’t degrade as quickly.

Synthetic blend

The problem with full synthetic engine oil is that it’s expensive. A less costly option is a synthetic blend or semi-synthetic engine oil that offers similar benefits without such an expense. It starts with a mixture of synthetic and conventional base oils and receives additives and detergents, typically better than you’d find in conventional oil. It’s a popular choice for carmakers and service shops alike. And in most cars, it’s become the minimum required grade.

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. Synthetic blends are formulated with different additives to better protect an engine against wear, high heat, cold weather and sludge build-up not found in conventional oils.

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.

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Short trips of less than 15 minutes make up the most severe driving conditions. If the engine doesn’t reach top operating temperature consistently, it can’t burn off water condensation, allowing sludge build-up to form.

Going deeper

An oil’s resistance to thinning in hotter temperatures is called the viscosity index. Although a higher second number is good, the oil also has to be robust, lasting for thousands of miles until the next oil change.

Oil tends to lose viscosity from shear, which is the sliding motion in the tight clearances between metal surfaces,such as those found in bearings. So, resistance to viscosity loss—called shear stability—is necessary to enable the oil to maintain the lubricating film between those parts.

Unlike antifreeze, 95 percent of which is made up of one base chemical (typically ethylene glycol), petroleum-based engine oil contains a mixture of several different types of base oils—some of which are more expensive than others. Oil companies typically pick from a selection of five groups, each of which is produced in a different way and in different viscosities.

The more expensive groups are more highly processed, in some cases with methods that produce a lubricant that can be classified as a synthetic. The so-called full synthetics contain chemicals that may be derived from petroleum but are so altered that they’re not considered natural oil anymore.

For example, one custom blend contained 10 percent polyalphaolefins (PAO), which is the most common type of chemical used as the primary ingredient in a full synthetic oil.

The base oil package in any oil makes up anywhere from 70 to 95 percent of the mix; and the rest is composed of additives. An oil with just 70 percent base oils isn’t necessarily better than one with 95 percent base oils.

Some base oils have natural characteristics or ones that derive from their processing, which reduce or eliminate the need for additives. Although some additives make improvements lubrication, they don’t necessarily have great lubricity on their own.

The ingredients in an additive package differ in cost, but price is just one factor. Some additives work better in certain combinations of base oils. Likewise, some less expensive base oils are a good choice for a blend because of the way they perform with popular additives.

Keeping an oil from thinning as it gets hot while it takes a beating from engine operation is one thing, but it’s also important to keep oil from becoming too thick. Using less volatile premium base oils to prevent evaporation is one approach. Evaporation of the base oil package not only increases oil consumption—it results in thicker oil, which decreases fuel economy.

Which oil should i choose?

The minimum type of engine oil your car requires is specified in the maintenance guide, which you should always follow.

What kind of oil does my car take

For naturally aspirated cars, it’s often conventional engine oil that’s the minimum standard. However, if you’d like extra protection for your engine, you can upgrade to semi-synthetic or full synthetic engine oil.

If your car has a turbocharger or supercharger, or if you have a high-performance model, the required type of oil is often semi-synthetic or fully synthetic. You should not downgrade to conventional oil as it doesn’t have the properties necessary to protect your engine as it needs.

Why so many oils?

Look in auto parts stores and you’ll see oils labeled for all kinds of specific purposes: high-tech engines, new cars, higher-mileage vehicles, heavy-duty/off-road SUVs, and even cars from certain countries. You’ll see a wide selection of viscosities.

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If you read your owner’s manual, you’ll know what oil the vehicle’s manufacturer recommended to use when it was brand-new. The manual may include a reference to Energy Conserving or Resource Conserving oils, which means that the oil passed a fuel economy lab test against a reference oil. While that doesn’t always translate to better fuel economy, most leading brands have at least some viscosities that are labeled as such.

Oil additives

Oil companies’ use of additives is another approach to improving and maintaining oil performance. High engine temperatures combine with moisture, combustion byproducts (such as unburned gasoline), rust, corrosion, engine-wear particles and oxygen to produce sludge and varnish, which can gum up and damage the engine.

Additives help maintain good lubrication by minimizing sludge and varnish. Here are the main categories of additive ingredients and why they’re important:

  • Viscosity-index improvers: These reduce the oil’s tendency to thin with increasing temperature.
  • Detergents: Unlike the kind you use to wash clothes, detergents in oil don’t scrub engine surfaces. They do remove some deposits—primarily solids. However, their main purpose is to keep surfaces clean by inhibiting the formation of high-temperature deposits, rust, and corrosion.
  • Dispersants: These disperse solid particles by keeping them in a solution so they don’t come together to form sludge, varnish or acids. Some additives work both as detergents and dispersants.
  • Antiwear agents: Sometimes the lubricating film created by oil breaks down, so antiwear agents have to protect the metal surfaces. A zinc and phosphorus compound called ZDDP is a long-used favorite, along with other phosphorus (and sulphur) compounds. If you must know, ZDDP stands for zinc dialkyl dithiophosphate.
  • Friction modifiers: These aren’t the same as antiwear agents. They reduce engine friction and thus, can improve fuel economy. Graphite, molybdenum and other compounds are used for this.
  • Pour-point depressants: Just because a 0 degrees Fahrenheit viscosity rating is low doesn’t mean that oil will flow readily at low temperatures. Oil contains wax particles that can congeal and reduce flow, so these additives are used to keep it flowing in the cold.
  • Antioxidants: With tighter emissions regulations resulting in higher engine temperatures, antioxidants are needed to prevent oxidation that thickens the oil. Some of the additives that perform other functions also serve this purpose, such as the antiwear agents.
  • Foam inhibitors: The crankshaft whipping through the oil in the oil pan causes oil to foam. Oil foam is not as effective a lubricant as a liquid stream, so oils have foam inhibitors that cause the foam bubbles to collapse.
  • Rust or corrosion inhibitors: These protect metal parts from acids and moisture.

How often should i change my oil?

Changing oil is routine, but the interval should never be neglected or extended beyond what your maintenance guide says. You can expect longer intervals from synthetic oil, typically, since it doesn’t degrade as easily, and 7,500 miles or more is common. For conventional oil, usually, an oil change should be performed every 3,000 to 5,000 miles.


How do I find out what oil my car takes?

You can usually find the oil grade stamped on the engine oil cap, or you can find the type and grade in your car’s owner’s manual or maintenance guide.

What car is 5W-30 oil for?

5W-30 engine oil is an extremely common grade and is used by hundreds of vehicle types. However, to know if it’s right for your engine, check the maintenance guide or oil cap for the grade you need.

What is my car oil capacity?

To find out how much engine oil your car needs, locate the Vehicle Specifications section in your owner’s manual. You’ll find how many quarts your engine takes, and get extra in case you require a top-up.

Above is information about What kind of oil does my car take? that we have compiled. Hopefully, through the above content, you have a more detailed understanding of Oil additives. Thank you for reading our post.

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