The word Synthetic is confusing; it describes a process, not a material. For example, White sand is synthesized into glass, but glass is never called "synthetic sand". Most people think that all synthetic oils are made of the same base, This is wrong! For most of the USA, there are mainly two types of synthetic oils (or as we like to say, synthetics are designer oils).

The most common is a PAO, short for poly-alpha-olefine, or easier to understand, it is synthesized petroleum oil. It is refined in a special process, or in simple words "synthesized". It still starts out by being pumped out of the ground. PAO’s are better than regular petroleum oil for handling heat, oxidation, low temperature startups and higher film strength. Drawback: PAO and petroleum are dynamic types of oil, you have to build up oil pressure and have rotation before a film is produced. Better said, you have to hydroplane the engine parts like you hydroplane a car in the rain, to create a film (or in the case of water-skiing, you have to build speed for the skier to get up and plane on the water). PAO’s are not very expensive because they are made from crude oil and produced in large quantities. You can usually tell when PAO’s are the main ingredient used as the cost of the 100% synthetic oil is less than $7.00 per quart.

The other main type of synthetics are synthetic esters, (diester, polyolesters, polyesters and complex esters). Motul® uses esters in its products. Esters are mostly made of vegetables, minerals, and animal fatty acids. Motul’s® esters contain a lot of coconut derivatives. Esters are much more expensive because the ingredients all have to be collected from natural resources and synthesized (a very expensive process) in smaller quantities. Esters have all the advantages of a PAO but more of them. Esters can handle heat better than PAO’s and when burned, esters leave far less coking deposits. Esters are static types of oils and are attracted to metal parts with an electro-chemical bond. This means no more metal to metal start ups. This also means that a film is there before the oil pressure light goes out preventing premature wear of high-stressed parts like cam lobes. The film created is up to 5 times stronger then petroleum oil.

The number one reason to run an ester synthetic oil is bond. The electro-chemical bond is made because the ester molecule is polar. Sort of like a refrigerator magnet. It is attracted to metal and sticks.The PAO molecules are neutral and act like a piece of plastic placed on the fridge. They just fall off. All commercial jet plane flying, use an ester synthetic of some type and not a PAO. You need to run an ester of some sort for maximum protection.

There are some companies calling level 3 petroleum base stocks synthetic. This oil is a good Petro oil. But it is not what we call a synthetic. The end result is that some oils are labeled incorrectly and are very inexpensive.

Until about 2000, these PAO base oils had an enormous advantage over mineral base oils in low temperature performance and in resistance to oxidation, which is critical in keeping the oil from forming acids. However, modern group-III oils can nearly match the performance of PAOs at about half the price. Because of this, PAO based oils are rapidly disappearing. There are new processes being investigated which may significantly cut the cost of producing PAOs, and make them an important component of oil again.