How Much “Synthetic” Is In My Oil?

Unlike food and drug companies, which must disclose the ingredients in their products, lubricant manufactures aren’t held to the same mandate, which can cause confusion if you’re shopping for synthetic motor oil. (Well, they are in Europe in Australia but not in the U$).  Store shelves are lined with oils described as “full synthetic,” “semi-synthetic,” “synthetic” and even “100% synthetic.”

When you crack the cap on those bottles, what are you really getting?

A basic understanding of the different base oils available and a few rules of thumb help you cut through the clutter and make a more informed synthetic-motor-oil purchase.

Crude oil composition

Crude oil and refining are at the core of manufacturing the base oils used in motor oil. Crude oil is composed of roughly 98 percent hydrocarbons (atoms of hydrogen and carbon bonded together), which come in hundreds of different combinations. The remainder includes compounds like sulfur, nitrogen, oxygen, metals and salts.

Oil refinery at twilightRefining crude into base oils

Crude oil refineries work much like a whiskey still. The crude is heated to distill or separate hydrocarbons into cuts, which include propane, gasoline, diesel and base oils used to make lubricants.

Base oils can undergo additional levels of chemical processing that remove impurities and arrange the hydrocarbon structures. The type of chemical process can affect the cost and quality of the base oil.

API base oil groups

The American Petroleum Institute (API) base oil classification is divided into five groups and is based on the paraffin and sulfur content and degree of saturation of the oil. The degree of saturation has nothing to do with water; rather it indicates the level of carbon molecules completely saturated with hydrogen bonds. Greater saturation equates to greater uniformity and stability.

Group I

Group I base oils are the least refined of all the mineral-oil groups. They’re usually a mix of different hydrocarbon chains with reduced saturation and uniformity. While some automotive oils use these stocks, they’re generally used in less-demanding applications.

Group II

Group II base oils are common in mineral-based (conventional) motor oils. They offer fair-to-good performance in the areas of volatility, oxidation stability, wear protection and flash/fire point. They have only fair performance in areas such as pour point and cold-crank viscosity. Cheap or fake synthetics can have a majority of this.

Group III

Group III base oils consist of reconstructed molecules that offer improved performance in a wide range of areas, as well as increased saturation and molecular uniformity and stability. These synthesized materials can be used in the production of synthetic and semi-synthetic lubricants although there is nothing synthetic by definition. These group systems were created after the fraud was OK’d by the BBB in 1999.

Group IV

Group IV base oils are made from polyalphaolefins (PAO), which are chemically engineered, synthesized (synthetic) base oils. PAOs offer excellent stability, molecular uniformity and improved performance. In the US if you see “Fully Synthetic” it may or may not have any percentage of this but 100% it will be 100%.

Group V

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

How much “synthetic” is in your oil?

Although there are no ingredients listed on motor oils, there are a few indicators that can be used to interpret the amount and quality of the synthetic base oil in the bottle.

  1. Synthetic blends (semi-synthetics) are just that – only partly synthetic, and the percentage of synthetic content can vary.
  2. While it’s not a hard-and-fast rule, manufacturers are open to greater scrutiny when they quantify a claim. Looking for claims like “100% synthetic” vs “full synthetic” or “synthetic” are an indicator that you’re likely getting more of the good stuff.
  3. Visit the manufacturer’s website and look at the product data sheet or technical data sheet for its oils. In this document, look for “Typical Physical Characteristics” or “Typical Technical Properties.” This section provides a high-level peek into the base oils used in the formulation. There are two numbers to pay attention to:
    1. Viscosity Index: Oils with a higher number include a better synthetic base oil that provides more protection to critical components over a wide temperature range by maintaining fluid thickness and the necessary fluid barrier between parts.
    2. Pour Point: measures the oil’s fluidity at cold temperatures and refers to the lowest temperature at which oil maintains its ability to flow. Lower numbers are likely to indicate a better synthetic base oil but there are also additives used in well known name brands which do well at pour points yet are not a premium product in other aspects..

A word of caution

While base oils are a fundamental element in formulating motor oil and determining its synthetic content, they’re only part of the picture. Additives make up the other part of the equation, and the quality and concentration of additives have a significant affect on the oil’s ability to protect.

In essence, look for an oil that offers good overall protection, not just one that’s formulated with a specific type of base oil. A good way to identify a high-quality synthetic is to look for quantifiable performance claims. For example, we advertise AMSOIL Signature Series Synthetic Motor Oil‘s excellent wear protection, as proven in a real-world test. It offers 75 percent more engine protection against horsepower loss and wear than required by a leading industry standard.*

There’s nothing confusing about that.

*As required by a leading industry standard. Based on independent testing of AMSOIL Signature Series 5W-30, in ASTM D7320 as required by API SN specification.

Conclusion

If the company has stockholders it’s likely you are not getting the top echelon of every additive available including the base stock. If it’s a privately held company who is devoted to the industry then you are very likely to be getting the best available and a more realistic price vs. cost to produce as the success of the company relies more on performance and reputation over advertising budget.

automatic transmission issues

Do Transmission Fluid Additives Work? John Baker| Feb 26, 2024 9:04 AM Walk the aisles of most auto parts stores and you’ll find multiple “mechanic-in-a-bottle”-type additives that claim to restore transmission performance. The claims made typically include some variation of the following: • Frees stuck valves to improve shifting • Fixes transmission slipping • Restores smooth […]

Understanding Oil Viscosity Viscosity is the measure of a fluid’s resistance to flow. _by David Hilgendorf|January 17, 2023 The physical properties of lubricants are measured by characteristics like viscosity, shear stability, high- and low-temperature performance, water resistance and volatility. Lubrication science seeks to optimize a lubricant’s performance by managing these properties using different base oils […]

Top 5 Skid Steer Maintenance Tips _by David Hilgendorf|September 29, 2023 Skid steers are built for tough construction, excavation, agricultural and other professional projects. Whether you’re clearing land, moving rocks or tearing down a wall, a skid steer is an excellent piece of equipment for many different jobs. But these nimble machines can be expensive […]

thermal runaway occurs when viscosity drops out and wear increases

How Often Should I Change Differential Fluid? Fluid change intervals depend on your vehicle, driving conditions and gear oil quality. Save time and cash first by improving the situation with this differential fluid solution! _by David Hilgendorf|Feb 26, 2023 A differential is a set of gears that allows a vehicle’s driven wheels to revolve at […]

New European oils for 2023 0W-30 and 10W-60

New AMSOIL Synthetic European Motor Oil Viscosities A new 10W-60 and 0W-30 for several BMW, Volkswagen and other fancy European cars. _by Brad Nelson|June 13, 2023 Those who know, know. The sophisticated engineering, finely-tuned performance and artistic styling of European cars can turn a daily commute into a grin-inducing experience. The design of these vehicles […]

EZ marine lower gear lube service

Service Marine Lower Units to Prevent Water Damage Preventing rust and other water-related problems in marine lower units. Most other Marine Gear Oils fail to make the grade. We learn more on that from our own customers when they make the switch. by David Hilgendorf|April 24, 2023 Water and gear lube don’t mix. Unfortunately, you […]