A base oil always serves as a foundation upon which all lubricants are created. However, when trying to decide which base oil is best for your needs, you may need a hand in understanding the differences. Trying to decide between mineral oil and synthetics can be confusing if you don’t know what to look for. Here is a quick break down on these different types of base oils, so that you can make an informed decision.

Oil Categories

  • Mineral Oil. Both high and low viscosity mineral oils are created from crude oil. This type can be produced with a variety of qualities, making it a good candidate for a range of applications.
  • Synthetic Oil. Synthetic oils are artificially created to include an array of qualities. They also are available in both low and high viscosity oil varieties, which makes them a strong contender when placed against standard mineral oil.


The above each have unique characteristics that make them better suited for certain applications. Mineral oil, for example is refined to specifically optimize the lubrication properties; whereas synthetic oils are tailored to achieve lubrication properties that may not be readily attainable with standard mineral oil.

Base Oil Grouping

Base oils are split into a couple of groups with the first 3 denoting specifically to mineral oils. Groups I, II, and III consist of mineral oils that have undergone increasing levels of refinement. Notably low viscosity mineral oils exist in group I, while high viscosity oils comprise group III.

  • Group I The most basic level of refinement, and one that has been used since the earliest days of refining. This extracts debris and components from the mineral oil, while keeping it at a low viscosity.
  • Group II This group is unique in that is uses hydrogenation to aid the refining process. This effectively removes more unwanted components from the finished product. This creates a medium viscosity oil, that can be a good middle ground between I and II, depending on what you need for your machinery.
  • Group III This group takes the process of hydrogenation from above and adds heat and pressure to the mix. This results in a product that is almost completely cleaned of any undesirable components.
  • Group VI This begins the first of two groups comprised of strictly synthetic oil. This particular group is specifically for polyalphaolefin, PAO, a type of oil that is most commonly used among synthetics. The advantages of this type include a higher viscosity, and improved performance in extreme temperatures. However they can under perform when it comes to additive solubility and overall film strength. Having been said, this synthetic oil is still comparable to group III mineral oil, and is something to consider if your job suits it.
  • Group V This group deals with all other oils including polyolester, phosphate ester, silicone, and diester, to name a few.


Keep in mind that viscosity increases with refining, the more impurities removes, the higher the viscosity. If you specifically need low viscosity mineral oils, stick to group I, or II at the most.

Making A Selection

When deciding which base oil to choose keep in mind that that they strong points and trade offs of each type. While high viscosity offers a greater film strength, low viscosity mineral oils offer more temperature variance and less consumption of energy overall. If you need additional help deciding, asking an expert can help you gain additional insight into which oil is best suited to your needs.

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