Engine Oils: Types, Viscosity, and FAQs


Engine oil is also referred to as motor oil and engine lubricant. Those are all different words all for the same thing. One thing is for sure, the engine oil is very important. In this article, I am going to talk about why your car needs motor oil, what are the different kinds and viscosities, and some will try to answer some of the frequently asked questions about engine oils.

Why Does Your Car Need Engine Oil

Car engines have lots of moving parts. As the engine parts move and rub against each other, the force of friction creates heat. The oil lubricates the engine to reduce friction, absorbs heat, and cleans the engine. It does this so that the parts can work effectively together without overheating.

But, over time engine oil breaks down and wears out. This makes it less effective in lubricating the engine and absorbing the heat. That’s why it’s very important to change the oil before it breaks down and causes engine damage.

4 Main Types of Engine Oil

Engine Oils Types, Viscosity, and FAQs

There are four main types of motor oil: Conventional oil, synthetic oil, synthetic blends, and high mileage oil. Each vehicle requires a different type of engine oil. So, I am going to help you understand which engine oil should you use for your engine and why.

1. Conventional Engine Oil

Conventional oil is the standard motor oil. It’s made from crude oil that’s taken from the ground. The oil is then refined and processed with additives at a factory. The biggest advantage of conventional engine oil is its low cost. It’s fairly effective as long as you choose the right weight and quantity for your engine.

Conventional oil comes in different types of viscosities and qualities. It’s usually used in cars with simple engines and for drivers with conservative driving styles. The disadvantage of conventional engine oil is that it’s less refined than the other type of motor oils due to the naturally occurring materials in it. It also offers a lower degree of protection for your engine compared to other oil types.

2. Synthetic Engine Oil

Today, over 50 percent of car owners use synthetic oil or synthetic blends in their cars. Full synthetic oil, also known as synthetic engine oil is chemically engineered so it’s generally more consistent, more refined, and overall better for your engine.

Synthetic engine oil lasts longer in time and distance compared to conventional oil. It also works better in both high and low-temperature extremes. But, all that comes with the price. Synthetic motor oil costs more than conventional oil.

3. Synthetic Blend Engine Oil

A synthetic blend engine oil is a combination of synthetic and organic oil. The synthetic blend engine oil provides better protection and performance than conventional oil and it lasts longer too. Drivers of pickup trucks and SUVs usually prefer to use the synthetic blend engine oil because it offers additional protection from oxidation and cold temperatures for vehicles that carry heavier loads,

Synthetic blend engine oil also tends to offer better gas mileage than conventional oil, but not as good as full synthetic oil. Cost-wise, it makes sense that synthetic blends stand in the middle ground. It costs more than conventional oil but less than full synthetic oil.

4. High-mileage Engine Oil

High mileage engine oil is enhanced with specific additives to minimize oil burn-off and oil leaks. It also provides better protection to engine seals, prevents oil evaporation, and improves performance for older cars with over 75 000 miles on them.

What is engine oil viscosity and which oil viscosity does your engine needs

Engine Oils Types, Viscosity, and FAQs

When you’re talking about motor oil, it’s not just all about the type, but also about the viscosity of the oil. Viscosity measures the resistance of the fluid to flow and it can be low or high. Simply put, viscosity means how thin or thick it is. For example, thin liquid-like water has a low viscosity, whereas, a thick liquid like honey has a high viscosity.

So, how do you know which oil viscosity your engine needs? You can find the correct engine oil viscosity for your engine in your car owner’s manual. The owner’s manual specifies the oil type and viscosity grade that your car needs. Often, you can find the correct oil viscosity on the oil cap as well.

When choosing motor oil, you can see its viscosity by reading a bottle or a can. Usually, you’ll see multiple numbers and letters. The letter W on the engine oil stands for winter. The number before the letter W is the winter oil viscosity parameter. It indicates how well the oil flows at zero degrees Fahrenheit.

It is very important to choose the correct viscosity parameter. Let’s say you live in a cold climate. Normally, oil thickens up as the weather temperature drops. So, in that climate, your car needs thin motor oil so it can flow more easily in your engine. In other words, if your engine oil is too thick, it’ll be harder to start your engine and it can reduce your gas mileage.

On the other hand, if you live in a hot climate, your car needs engine oil that doesn’t become too thin when it’s hot. In other words, if you live in a hot climate, your car needs motor oil with higher viscosity (a higher number before the letter W, for example, 10W).

The number after the letter W stands for the summer oil viscosity parameter which is based on viscosity at 212 degrees Fahrenheit. Basically, this is the oil’s ability to resist thinning out at higher temperatures. For example. 10W-30 engine oil thins out at a higher temperature faster than 10W-40 engine oil.

Engine Oil Standards

Engine Oils Types, Viscosity, and FAQs

There’s a group called ILSAC which stands for International Lubricant Specification Advisory Committee. They set the performance standards for motor oils used in gas-powered cars and light trucks. ILSAC approved GF-6 which is the new standard for motor oil designed to improve fuel economy and enhance engine capabilities.

The new standard allows thinner engine oils to reduce friction and increase fuel economy. This means better protection against wear in a stop-start equipped engine, better protection of timing chains, and protection against low-speed pre-ignition (LSPI). LSPI is actually a problem that can happen in modern turbos when the fuel ignites too soon which is bad because the explosion can damage your engine. So, preventing LSPI helps carmakers to tune the engine for greater efficiency.

GF6-A is for existing cars. It covers the current APIs and oil viscosities of 0W-20, 5W-20, 5W-30, and 10W-30. It meets all specifications for these current oils, in addition to meeting the latest GF-6 specifications. It’s backwards compatible which means it offers some of the benefits of the new standard, but it works fine in cars designed for the older standards. That being said, even though it’s backwards compatible GF-6A is really not intended for engines older than maybe the latest generation of production engines, or roughly back to the mid1990s.

GF-6B is the new standard only for 0W-16 low viscosity engine oil and it’s not backwards compatible. GF-6B standard is mainly aimed at turbocharged gasoline direct-injected engines tasked with achieving fuel economy levels and it’s aimed at engines that were made in 2017 and newer.

How Frequently Should You Change Your Engine Oil

How frequently you should change your engine oil depends on many factors such as vehicle age, oil type, the way you drive, and where you live. It used to be normal to change the oil every 3000 miles. But, with modern lubricants, many engines nowadays have recommended engine oil changing intervals of five thousand to seven thousand miles.

You might want to consider changing your oil more often if you tend to drive at high speed. That also goes if you have an older engine or live in an area that’s particularly hot, cold, or dusty. If your engine requires full synthetic engine oil, then it could even go as far as 15000 miles.

How Do You Know If Your Engine is in Need of an Oil Change

So, how do you know if or when your engine is in need of an oil change? There are several common signs and the most obvious warning is you’re having an oil problem that will come from the car itself. Newer cars come equipped with an oil monitoring system. The oil change indicator or the check engine light on your dashboard will turn on when there’s not enough oil in the system. In that case, you can check the level of your engine oil by checking the engine dipstick.

Another warning that your engine is in need of an oil change is increased engine noise. When your car has sufficient motor oil, the oil helps protect the engine parts. The engine stays quiet because the oil is lubricating all the metal parts. But, let’s say your oil level is low. This means there’s not enough engine oil to lubricate the engine parts, so the parts will brush against each other and the result is you may hear knocking or rumbling sounds. That’s never a good thing because basically, your engine is tearing itself apart bit by bit.

If you sense an oil smell inside your car, it could mean you have an oil leak. If you also smell gas or exhaust fumes, your car might be overheating. Also, if you see the exhaust smoke coming out of your tailpipe, it’s time for an engine checkup. Either way, you should take it to the shop to get it checked out as soon as possible.

If you have excessively high mileage in a particular month, you should consider changing your oil a bit sooner than your normal schedule.

My Engine Oil is Black, Should I Change It?

A common myth about the color of the oil is that black engine oil must always be changed. Actually, that’s false. Motor oil darkens especially when the oil is exposed to high engine temperatures and therefore oxidizes. The motor oil can also darken as it absorbs byproducts from combustion. The dark color itself doesn’t mean the oil is dirty or no longer doing its job. Instead, what you should watch out for is how dirty the oil is. If the oil is gritty or grainy, then get it changed as soon as possible.

Do I Need Thicker Motor OIl For Extra Wear Protection?

You don’t need to use thicker engine oils for extra wear protection. Thicker motor oil can be better for older engines with parts that have worn down over the years. But, let’s say you have a newer car. If you use oil that’s thicker than recommended for the engine, it can actually decrease engine efficiency. Many modern cars actually recommend lower viscosity for better fuel economy.

It’s best to use the viscosity weight recommended by the engine manufacturer. This is for the best because the manufacturer knows their product the best. They know how best to protect the moving parts based on the design and surface roughness.

Are All Oil Additives The Same?

No. Not all oil additives are the same. Engineers developed different additives to help engines in different ways. For example, some additives help the oil to perform better under high pressure and heavy use like in racing engines. Other oil additives help older high mileage cars to last longer by preserving seals. The point is, different additives are for different purposes.

There is a myth about additives improving engine performance. For sure, additives help the engine, but they can’t add horsepower to your engine or improve gas mileage.

Do Synthetic Engine Oils Cause Leaks?

When synthetics first came out in the 1970s, they caused wear and tear to seals and gaskets on engines. Today, that’s not the case. Modern synthetics have come a long way. In fact, synthetic engine oils do a better job than conventional oil in protecting engine parts, especially at extreme temperatures.

Do I Need To Change The Oil Filter Every TIme?

Oil filters are important because they remove a lot of the dirt, grime, and sludge from your engine. But, the filter’s performance degrades over time as it removes more and more contaminants. Oil filters are usually designed to last one oil cycle. So, yes. You should change your filter every time you change the oil.

Car Fluid Guide

Hi there. I am the owner and author of carfluidguide.com. Here on this blog, I will share my knowledge about car fluids that I have accumulated over the past 10 years of working on cars. Stay tuned for more amazing content.

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