What is the Best Conventional Motor Oil in 2024?

If you are in a hurry and just want to find out what the best conventional motor oil is, then we recommend AmazonBasics Conventional Motor Oil as the best one.

A healthy engine is a happy engine. And a happy engine guarantees great performances for a long time.

The number one best way to keep your engine healthy and happy is giving it a fresh dose of its recommended motor oil.

A regular oil change is a small maintenance job that helps keep your engine in top shape for miles to come. Yes, it’s an extra cost on top of gas and insurance. But as a wise person once said, prevention is cheaper than cure.

We’ve created this guide to help you select the best conventional oil for your vehicle.

Combined with regular maintenance, the best motor oil will get you where you need to go while ensuring that your engine runs at peak performance for years to come.

Here are the best conventional motor oils we recommend:

why you should trust us

All of our reviews are based on extensive market research, expert input, and practical experience. We invest time and resources to analyze the products. This way, we can offer you genuine, accurate guides to help you get the best pick for your needs.

What is Conventional Motor Oil?

Conventional motor oil, aka regular motor oil or mineral motor oil, is a lubricant that is derived directly from crude oil. Yep, motor oil derives from the same good ol’ fossil fuel that we all know.

As opposed to synthetic motor oil, regular oil refinement process is shorter and simpler. Thus, though synthetic etic oil is just plain better, conventional oil wins in the cost department.

Although the properties of synthetic oil are definitely superior, regular oil will protect your vehicle’s engine just fine in most situations.

The most important thing you can and should do to keep your car running smoothly is to follow your vehicle manufacturer’s recommended service intervals. That is changing the vehicle oil and oil filter at the recommended times. Regularly.

In temperate climates, if you don’t drive much more than 6000 miles (10000 km) in a year, and you perform regular oil changes according to your vehicle owner’s manual, conventional oil will be just fine.

On the other hand, if any of the previous conditions doesn’t hold, you might be better off investing in a good synthetic oil.

How to Choose the Best Motor Oil for Your Vehicle

Viscosity Rating

The first and most important thing to know is your vehicle’s engine recommended oil viscosity rating. The best engine oil for your vehicle will be one with the recommended rating.

The viscosity rating can be found, like most things, in the vehicle owner’s manual. Alternatively, it is sometimes indicated right on the vehicle’s oil cap.

The rating is usually composed of two numbers separated by a W, e.g., 5W-30.

Those numbers represent the oil viscosity, that is its thickness, when cold, and when hot. Oil is thicker at lower temperatures and thinner at higher temperatures.

A visual explanation of motor oil viscosity rating

In other words, the numbers represent how the oil behaves at cold and at hot temperatures. The first number represents the behavior when cold (the W stands for winter by the way). The second represents the behavior when hot (i.e., at operating condition).

The desired oil behavior depends on the vehicle engine, hence the recommended viscosity rating.

Generally speaking, thicker oil

  • provides greater protection for your engine parts
  • but it will be harder to get flowing, especially at the start when the engine is still cold, and could thus end up causing engine wear (because the engine will operate without oil temporarily)
  • because of the higher viscosity, it can act as a dampener for the engine motion, and can thus decrease fuel efficiency.

Thinner oil, on the other hand,

  • provides a thinner film between the moving motor parts, and thus less protection
  • but it will be easier to get flowing, especially at the start of the engine
  • because of the lower viscosity, it dampens less the engine motion and thus usually yields a higher fuel economy.

In synthesis, at lower temperatures, there’s a risk that the oil gets too thick and doesn’t flow as it should, whereas, at higher temperatures, there’s a risk that it gets too thin and doesn’t protect the engine as it should.

As far as the viscosity rating

  • the lower the first number, the better the oil will flow at lower temperatures (e.g., 5W oil will flow better than 10W oil at lower temperatures)
  • the higher the second number, the less thin the oil will be at higher temperatures and thus the better it will protect the engine (5W-40 oil will be less thin than 5W-30 oil at higher temperatures).

However, what we’ve just said is just for your personal education and curiosity. It is absolutely crucial to follow the oil viscosity recommended by the vehicle manufacturer.

Do not buy oil with a different rating out of your own volition. Maybe you’re in a colder climate and thus you may think you need a lower W rating. Or maybe you’re in a hotter climate and you’re considering a higher hot rating. Unless your vehicle owner’s manual has explicit guidelines on the matter, don’t. Just don’t. Simply use the recommended viscosity!

We’ll repeat that again: the desired oil behavior depends on the vehicle engine. Not all engines are created equal. Each engine expects a particular behavior from its oil. Your vehicle’s manufacturer obviously knows best. Hence, follow the recommended viscosity rating.

Type of Engine: Gasoline or Diesel

This one’s pretty simple. You want an oil that is appropriate for your type of engine.

If you have a gasoline engine buy a gasoline motor oil. If you have a diesel engine buy a diesel motor oil.

There’s actually a link between the type of engine and the recommended viscosity. Since diesel engines’ operating temperatures are usually higher than gasoline engines’, diesel motor oil will usually have a higher recommended “hot viscosity rating”.

But this is just for curiosity’s sake. You don’t actually need to know this. Simply buy an oil with the recommended viscosity and compatible with your engine type.

Luckily, some newer oils are actually compatible both for gasoline and diesel engines. But you should always check if that’s the case.

It will be usually indicated explicitly on the oil jug. In the case that it isn’t, you can check the API oil certification labels on the back of the container.

API Certification Labels

The API donut and starburst labels

In the US, every container of reputable motor oil will have the API (American Petroleum Institute) donut and starburst labels indicating the service rating of the oil.

The API donut tells you if the oil meets the current S (for gasoline) or C (for diesel) service rating.

By the way, S stands for Spark ignition (i.e., gasoline) engine, while C stands for Compression ignition (i.e., diesel) engines. That should make it easier to remember!

The letter following the S or C indicates the “version” of the rating. Generally, the higher it is, the better the oil will be.

Additionally, newer versions are always “backward compatible” with older requirements. Thus, if for example your vehicle’s manual asks for an SJ rated oil, you can use an SJ, or SL, or SM, or SN oil and you will be fine.

As a recommendation, it’s better not to go lower than SJ, as these oils are obsolete and could cause damage to your engine.

The API donut also provides the SAE (Society of Automotive Engineers) viscosity rating of the oil and tells you if the oil has passed the Energy Conserving test.

Finally, the starburst symbol indicates that the oil has passed the tests listed for the S or C reported service level.

These are the Best Conventional Motor Oil Brands

As we said, you should always follow your vehicle owner’s manual for the recommended oil viscosity. Sometimes, however, the manual will also recommend a particular brand of oil. This particular brand recommendation, if present, can be safely ignored. The vehicle manufacturer will most likely have a partnership with that oil brand. And that’s why they are recommending it. That’s not necessarily the best oil brand.

As long as you follow the recommended viscosity rating, most oil brands will do. So you might as well choose the best conventional motor oil brand for your vehicle.

In our experience and according to our extensive research, these are the best non-synthetic motor oil brands.


Castrol is one of the most famous lubricants company in the world. Founded in 1899, it operates in over 40 countries, producing lubricants for motorcycles, two-stroke, four-stroke, gas, and diesel engines. Their tagline says it best: it’s not just oil, it’s liquid engineering. Many consider it the best engine oil brand on the market.

Two of their most recommended products are the Castrol GTX 10W-40 Motor Oil and Castrol GTX Diesel 15W-40 Motor Oil.


Shell is a Dutch-British oil and gas company headquartered in the Netherlands and incorporated in England. It is one of the oil and gas “supermajors” and the third-largest company in the world.

Shell products are renowned and appreciated in the automotive, industrial, marine, motorcycle, and racing industries. Their motor oil products garner the endorsement of many car enthusiasts for its high-performance formula. For over 40 years, their ROTELLA line has delivered heavy-duty diesel engine oils offering unrivaled protection and performance.

One of their most recommended products is the Shell Rotella T4 Triple Protection Conventional Diesel Engine Oil.


Pennzoil is an American oil company founded in Los Angeles, California in 1913. Pennzoil is an official long-term recommended motor oil Fiat Chrysler, BMW, Mini, Rolls-Royce, Hyundai, Chevrolet, Ford, Ferrari, Iveco, Ducati, and Opel in the United States. And there’s a reason for that. It is one of America’s most trusted motor oil.

Two of their most recommended products are the Pennzoil Conventional 10W-30 Motor Oil and Pennzoil Conventional 10W-40 Motor Oil.


No, we’re not kidding. AmazonBasics may not be a well-known brand when it comes to the automotive industry, but in recent years, Amazon’s own line of products has expanded at a rapid pace to all types of markets. And their motor oil offer is one of the best we’ve seen in quite a long time.

All of their oils have the best and most recent API certifications to date. And as if that weren’t enough, their products, like most AmazonBasics products, are super affordable. What’s not to like?!

AmazonBasics’ motor oil is manufactured by Warren Distribution, Inc., which is North America’s largest manufacturer of private label lubricants.

Two of their most recommended products are the AmazonBasics 10W-40 Conventional Motor Oil and AmazonBasics 5W-30 Conventional Motor Oil.

These are the Best Conventional Motor Oils

Alright, here we are. In our experience and according to our in-depth research, these are the absolute best conventional motor oils on the market.

Best Conventional Gasoline Motor Oil: AmazonBasics Conventional Motor Oil

Formulated to keep engines properly lubricated and protected, this oil is designed to help prevent buildup that can cause rust and corrosion. AmazonBasics’ conventional motor oil has high resistance to viscosity and thermal breakdown, while also helping reduce exhaust emissions.

If you’re concerned about the fact that the brand is not that well-known in the automotive industry, don’t be.

Behind AmazonBasics’ motor oil there’s Warren Distribution, Inc., which is North America’s largest manufacturer of private label lubricants.

Their oil is API SN Plus and ILSAC GF-5 rated and certified. And these are the most up-to-date and strictest certifications to-date.

Finally, our opinion and general consumer feedback of this oil are through the roof.

At a very accessible price, this oil has absolutely deserved the best conventional gasoline motor oil spot in our review.

You can get the AmazonBasics Conventional Motor Oil in 5W-30, 10W-40, and 20W-50 viscosities.

Best Conventional Diesel Motor Oil: Shell Rotella T4 Triple Protection Conventional Diesel Engine Oil

Shell Rotella T4 is a multi-purpose heavy-duty diesel engine oil engineered to help you get long and healthy engine life in a variety of applications and duty cycles.

It provides extra protection against diesel engine problems, like soot and harsh deposits that your motor faces every day.

Shell Rotella T4 is designed to provide superior protection, conforming to the strict requirements of engine oil technology and can be used in diesel engines where API CK-4, CJ-4 and below is required.

This 15W-40 conventional diesel motor oil is a versatile product that can be used in a wide variety of heavy-duty, commercial vehicles and pick up trucks, as well as most modern diesel cars. It is also available in 10W-30 viscosity.

Its special formulation helps to keep the engine cleaner, giving more reliable engine protection and thus prolonging engine life.

Honorable Mention: Castrol GTX Motor Oil

Castrol GTX Motor Oil is one of the world’s most trusted gasoline engine oils. It protects against problems that your gasoline motor faces each and every day.

This premium conventional motor oil has been helping to extend engine life for over 50 years. It has evolved to meet the needs of consumers and vehicle manufacturers since 1968 and continues to innovate and remain a trusted brand today.

The Double Action formula of Castrol GTX gives superior protection, cleaning away old sludge while protecting against new sludge formation, better than tough industry standards.

Castrol GTX Motor Oil is API SN certified and comes in 10W-30, 10W-40, and 20W-50 viscosities.

Though a bit more expensive than our best conventional gasoline motor oil pick, it was and still is an excellent product.

What If I Can’t Find My Vehicle Recommended Oil Viscosity?

If you don’t know your vehicle recommended oil viscosity, you can just check your trusty vehicle owner’s manual.

If you can’t check the manual, you may try and have a look at the vehicle oil cap. Sometimes the oil cap reports the recommended viscosity.

Once you know it, you can come back here and select the right viscosity from the best pick.

However, if you’re just not able to find the vehicle recommended oil viscosity, or if the viscosity is not among the ones available for our top picks, don’t despair. We got your back.

Simply trust one of the best motor oil brands we recommended before. They provide great motor oils that are consistently rated as the best in the industry.

Most of these brands provide a website with a specialized search function to help you select the best oil for your vehicle.

Then, you just select the right model for your car and buy it.

Here’s a step-by-step procedure:

  1. Select one of the recommended best motor oil brands. We recommend Castrol as the most versatile brand with the largest selection.
  2. Go to the brand website and search for your exact vehicle model to obtain the recommended motor oil specific for your vehicle.

    These are the search pages of the recommended best motor oil brands:

  3. Once you have the brand’s recommendation for the right motor oil for your vehicle, simply plug it in the search box below to get the best price on Amazon and buy it (if you can’t see the search box then please disable your ad blocker for this site).


As long as you perform regular oil changes according to your vehicle owner’s manual, conventional motor oil will be perfectly fine and will save you a lot of bucks in the long run.

The best conventional motor oil on the market that we find ourselves recommending, again and again, is AmazonBasics Conventional Motor Oil. It’s just so good and so affordable to make it a no-brainer.

Should you need a diesel motor oil though, definitely go with Shell Rotella T4 Triple Protection Conventional Diesel Engine Oil. You can’t do better than that.

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