Are all Synthetic Oil Groups the Same? Group III vs IV vs V

John Baker|Feb 06, 2018 11:27 AM

The simple answer

No. In fact, there are wide performance differences between base oil categories. Generally speaking, Group IV base oils offer the best performance, Group III second best, and so on in reverse order. But be forewarned – there are exceptions. And, you can’t judge motor oil performance solely on base oil type. You must take into account its entire formulation, including the additives.

The detailed answer

Ever find yourself in an awkward conversation from which you want to escape? Start talking about base oils and the relative merits of each category. Your adversary will immediately excuse himself.

To ease your study of the topic, it’s broken down into the following common questions:

What are the different base oil categories?

The American Petroleum Institute (API) developed a classification system for base oils that focuses on the paraffin and sulfur content and degree of saturation of the oil. The saturate level indicates the level of molecules completely saturated with hydrogen bonds, leaving them inherently un-reactive.

Translation: they’re more resilient to chemical degradation, meaning they last longer and perform better.

There are five groups in the classification system, ranging from Group I – Group V:

• Group I Characteristics

Group I base oils are the least refined of all the groups. They are usually a mix of different hydrocarbon chains with little uniformity. While some automotive oils use these oils, they are generally used in less-demanding applications.

• Group II Characteristics

Group II base oils are common in mineral-based motor oils. They have fair-to-good performance in the areas of volatility, oxidation stability, wear prevention and flash/fire point. They have only fair performance in areas such as pour point and cold-crank viscosity.

• Group III Characteristics

Group III base oils consist of reconstructed molecules that offer improved performance in a wide range of areas, as well as good molecular uniformity and stability. These synthesized materials can be used in the production of synthetic and semi-synthetic lubricants.

• Group IV Characteristics

Group IV base oils are made from polyalphaolefins (PAO), which are chemically engineered synthesized base oils. PAOs offer excellent stability, molecular uniformity and improved performance.

• Group V Characteristics

Group V base oils are also chemically engineered oils that do not fall into any of the categories previously mentioned. Typical examples of Group V oils are esters, polyglycols and silicone. As with Group IV oils, Group V oils tend to offer performance advantages over Groups I – III. An example of a mineral-based Group V exception is a white oil, a very pure lubricant used in industries ranging from cosmetics to food processing.

Are the API group classifications progressively better?

In other words, is a motor oil made from Group III base oils better than one made from Group II base oils, and so on?

In general, yes. Unlike your food, which generally gets less healthy the more it’s processed, base oils offer improved performance as the level of refinement/processing increases.

But there are side cases that smash that rule of thumb.

Some motor oils made from Group III oils can outperform some Group IV motor oils. That’s because the final formulation is a function of the base oils and additives working in tandem. Like base oils, additives come in a range of qualities. So you could have a Group III oil with top-shelf anti-wear, anti-oxidant and other additives that outperforms a Group IV motor oil, even though Group IV base oils provide more pronounced benefits than Group III base oils. The point is, a motor oil can’t be judged solely by its base oils – you need to take the entire formulation into account.

Then we have the Group V category, which is a sort of catch-all for anything that doesn’t fit into the other four groups. In fact, some Group V oils are completely unsuitable for automotive use.

Are Group III base oils “synthetic?”

Yes, in most countries anyway.

A true definition for the term “synthetic oil” has been difficult to reach, although it has generally been accepted that the term represents those lubricants that have been specifically manufactured for a high level of performance. Group III base oils with very high viscosity indices can be called synthetic oils in most countries.

Historically, it was widely accepted that only Group IV base oils made from PAOs were true “synthetics.”

A famous lawsuit between Mobil and Castrol changed that. Mobil charged that Castrol was falsely marketing its Syntec motor oil as a synthetic oil although it wasn’t made from PAO base oils. Mobil’s claim was based on results of independent lab testing that showed samples of Syntec it obtained as early as December 1997 contained 100 percent mineral oil.

The two sides battled it out, but in a landmark 1999 ruling, the National Advertising Division of the Council of Better Business Bureaus ruled that Castrol Syntec, as then formulated, was a “synthetic” motor oil.

Debate raged then, and still rages today. You can find all kinds of purists populating Internet forums who refuse to recognize Group III oils as “synthetics.” For them, it’s PAO or nothing.

Try not to get caught up in the “my-base-oil-versus-your-base-oil” cage match. The base oils that go into the oil aren’t as important to your engine as the performance that comes out of the oil. Look for motor oils that offer performance claims backed by industry-standard testing or real-world results. That’s what’s really important.

If you really need to know which base oils a formulation uses, you’ll have to do some investigative work since oil companies protect that information as proprietary.

For details, check out this post: How Much “Synthetic” Is In My Oil?

Are synthetic base oils magic?

Ok, that’s not what people really ask. But many falsely think synthetic base oils are not refined from crude oil and that switching to only synthetic lubricants could drastically reduce our dependence on foreign oil and non-renewable sources. If synthetic base oils aren’t made from crude oil, from what raw material are they made? Unicorn horns and rainbow dust?

Synthetic base oils are made from crude. But they’re much more highly refined than conventional base oils. The chemical reaction process used to make synthetic base oils removes the impurities inherent to conventional base oils, such as sulfur and waxes. This results in a higher-performing product that’s much better for your engine.

What is Synthetic Motor Oil?

Ed Newman|Aug 18, 2017 8:19 AM

As most of my friends know, and you now as well, I listen to audio books during my daily commute. My current book, about history’s first billionaire, is titled “Titan: The Life of John D. Rockefeller, Sr.” It’s a massive book about a massively complex man, and it’s been a fascinating “read.”

Here are a few things I’ve learned:

1) Like most historical figures, there is a complex human beneath the reputation. Rockefeller has been called the most feared and ruthless businessman in our history, and simultaneously the most generous.

2) Kerosene was the main consumer product derived from crude oil at the time. The internal combustion engine did not yet exist, but Rockefeller grew rich thanks to the abundance of kerosene lamps in the nation’s homes.

3) Pennsylvania was the first region in which oil was discovered. Eventually, oil was found in Lima, Ohio, but its composition was chemically different, and the kerosene left a film on the lamps.

4) Lubricants literally played a major role in greasing the wheels of progress. The Industrial Age was all about machines enabling industry to be more productive, which generated wealth for industrialists.

5) Around the time the electric light bulb was replacing kerosene lamps, cars were replacing the horse and buggy. The 20th Century became the century of Big Oil.

Well…that’s a deep subject

If it seems like I’m not answering the question posed in the headline, it’s because I wanted to bring you in through a back road. Item three in the above list notes that oil is chemically different based on its origins. I learned this years ago because my West Virginia kin had an oil well. I remember walking up the hill to the well when I was young. The adults discussed how the oil company said the oil was not worth as much as higher-quality crude. I may have my facts jumbled, but I believe they said it would be suitable for natural gas and would therefore not fetch as much money.

Distillation nation

Crude oil contains hundreds of different kinds of hydrocarbons. Oil refineries distill crude and separate it into various products, like gasoline, jet fuel, diesel fuel, heating oil and asphalt. And the base oils that go into motor oil.

Refining is a process of physically separating light oil components from heavy ones. Crude oil contains a multitude of different kinds of molecules. Many are similar in weight, but not in structure. The refining process cannot distinguish such molecules, so a wide assortment of molecules is present in the finished lubricant made from crude oil stocks.

Some crude oil molecules are not beneficial to the lubrication process. For example, paraffin causes refined lubricants to thicken and flow poorly in cold temperatures. Molecules containing sulfur, nitrogen and other elements invite the formation of sludge and other by-products of lubricant breakdown, especially in high-temperature applications.

The assorted molecules of refined lubricants also have different shapes, making lubricant surfaces irregular at the molecular level. As lubricant layers flow across one another during the lubrication process, these irregularities create friction, which consumes power, reduces efficiency and increases heat and wear.

How synthetic oil is different

Rather than being refined from crude oil, synthetic lubricants are chemically engineered from pure chemicals using a process called organic synthesis. Organic synthesis is when you combine two things from nature to create something that does not exist naturally. This process gives synthetic oils significant advantages over refined oils.

Products made from a barrel of crude.

Synthetic oil molecules are uniform, not irregular. This uniformity helps them resist thinning in heat and thickening in cold, which improves protection throughout the engine’s operating temperature range.

Their molecular uniformity also reduces friction as the lubricant’s layers slide across one another. Reduced friction increases energy efficiency for greater fuel economy and maximum power. It also reduces heat and wear for longer equipment life.

Another feature of synthetic oils is that they are designable. Many different kinds of base oils may be used to create synthetic lubricants, allowing a synthetic to be designed for virtually any application. Some base oils are ideal for use in extremely cold environments. Others are perfect for use in extreme heat. Some are extremely safe in applications in which refined lubricants pose a fire or explosion hazard. Refined oils simply do not offer the design flexibility of man-made synthetic oils.

This design flexibility allows synthetics to be tailored to the needs of everyday applications, such as automotive engines, commercial equipment or industrial machinery. That specificity helps ensure maximum life, horsepower, performance and fuel economy from the lubricated system.

Bottom Line

If all this seems a little technical – to be honest, I did take a little heat for writing such a technical post this week – here’s all you really need to know about synthetic and conventional oils. The AAA made a big splash this summer when it laid out its findings in a study that demonstrated the superiority of synthetic oils. Everyone seems to be talking about it, from the AutoBlog to The Drive and even the folks at Business Insider. The titles are pretty straightforward, but I especially like the one from BI: “A new study by AAA puts to rest one of the most common questions car owners have.” In other words, “that settles it.”

Now for the next question: What are you going to do about it?

Here’s my recommendation. Visit this page and find the AMSOIL synthetic lubricants for your vehicle. Experience firsthand what “better” really means.

Category: Knowledge Base