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History of Engine Oil
SYNTHETICS IN THE USA. @1996 rewrite ~2000©
In the USA there are a few different types of synthetic base stocks used in engine oils. We will just touch on two in this technical / sales paper.
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.
Let’s explain why handling higher running temps is important.With petroleum oils there is a much better risk of failure from volatility problems than with synthetics. Why?
Have you ever burned butter while cooking? Yes, everybody has burned butter! The running temp or maximum temp is low. When butter reaches its maximum running temp it starts to evaporate (volatility) then it carbonizes and then it sticks to the metal pan. Now compare butter to vegetable oil in which you deep fry french fries. The only way to heat vegetable oil so hot as to make it carbonize, you would almost need a direct flame.
Petroleum oil is like butter as far as handling heat! Synthetics are like vegetable oil - synthetics won’t burn up and stick to your engine parts or go out the breather as fast as petroleum oils will. Remember esthers leave almost no deposits if they do burn this is the second reason to run a synthetic oil. Because you’re not supposed to have extreme heat problems everyday.