Did you miss out on the geography lesson that covered the creation of oil? No problem! Before we go into details we will give you a short recap of the basics.
Oil is the end product of organic matters in combination with an inadequate supply of oxygen. During millions of years of burial, chemical reactions triggered by the elevated temperatures at depth slowly transformed some of the organic material into liquid and gaseous compounds of hydrogen and carbon (hydrocarbons). The hydrocarbons are the combustible materials of oil and natural gas. The compaction of muddy organic sediment forced the fluids and gases into neighbouring beds of permeable rock such as sandstones or porous limestone. These huge pockets of oil and gas are the lucrative target for the offshore oil drilling industry today.
From crude to perfection
Once it has been pumped up, the raw material, called crude oil, is transported to land and distilled to separate the crude oil into different sorts of base products. This fractioning is made under reduced pressure and the lubrication base-oils are separated at approximately 350 degrees Celsius. Often the crude oil in lubrication fluids originates from the so called Sweet Arabian Crude and the chemical process is mainly operated from France and England.
The art of lubricants
Ever heard of Tribology? It is actually the science of friction, wear and lubrication. The word Tribo comes from the Greek word for rubbing. It all comes down to 50 some base oils, approximately 300 additives to improve certain features and a total of 650 recipes that together form the huge base of alternatives to find the optimal lubrication fluid for a certain product. The cost to find a perfect match for a recent car model can jump up to as much as US$ 2 million. When you think of the speed at which new car models appear on the market today, the price tag for serious oil manufacturers to keep up with a professional series of oils in the assortment becomes very high.
David often beats Goliath…
Often the biggest guy on the block runs the business, no matter what. But in the oil business it is often the other way around. Small research and development companies form alliances with their partners within the production industry and they tend to keep a close bond to each other for a long period of time. This means a tremendous amount of time and money saved when products are developed together with the lubrication manufacturer. The lubricant and the product grow side by side and engineers from both camps agree on the basics to produce the ultimate product with the ultimate lubrication. It’s no secret that the small, fast-moving R&D companies can offer better technical support and know-how in comparison with the mega companies in the oil business. Some of the R&D companies actually run their own brands with great success on the market. STATOIL is the third largest crude oil supplier in the world and one of the biggest players in the European natural gas business. In the North Sea STATOIL is the No. 1 producer of oil and gas. It was way back in the beginning of 1980 when contact was first established between Öhlins and STATOIL. Öhlins wanted to learn more about hydraulic fluids and STATOIL provided the know-how. Today, more than 20 years later, STATOIL is a vital part of the R&D phase when Öhlins is designing a new product.
The Lubricating Regime…
It all starts here, with the almighty Lubricating Regime. The Regime is based on the classic Stribeck curve, invented by the German scientist Richard Stribeck (1861- 1950). Stribeck’s investigation of periodical bearing friction, as a function of load and speed, was extremely important, as he showed the possibility of finding a point of minimum friction for lubricated applications. He also showed that the friction for sliding bearings started at high friction at low speeds, decreased to a minimum friction when metal to metal contact stopped, and then increased again at higher speeds, which is the well known Stribeck curve. As mentioned above, the type of product, the design of the moving parts and the area of use always end up in a point on the Stribeck curve. The recipe for a perfect lubrication fluid for a certain application can almost be pinpointed after finding the product’s position in the diagram. At the beginning of the diagram the speed is almost zero and the distance between two moving surfaces is close to zero. The pressure on the meeting materials is extreme and the risk for serious wear is imminent. When moving out on the Stribeck curve, the oil tends to differ in its recipe because of the greater distance between the adjacent surfaces and the increased speed of the lubricant. At the far end of the curve the adjacent surfaces very seldom or never meet and the lubricant has a very different design than the first one mentioned.
The enemies…
A lubrication fluid doesn’t live a happy life. Most of the time is spent in a sealed compartment without windows and in constant conflict with just about everything.
STATOIL is in the very forefront of R&D within this area and PERFORMANCE Magazine got an exclusive lesson with Professor Thomas Norrby, R&D Manager at STATOIL Lubricants. Few people know the enemies better than him.
Heat
The thermodynamic capacity is a measure of the heat absorption a lubrication fluid is designed to tolerate. This capacity is often measured in Cp and is approximately 1,9kJ for every +1 degree Celsius and kilo of a lubricant at room temperature.
This ability to absorb heat is very important in some areas of use and can be altered by additives. Heat is normally not the biggest threat within the shock absorber business but in some areas, such as Motocross and Enduro, the fluid tends to work hard inside the tube and the temperature can get as high as 150- 170 degrees Celsius.
At these temperature levels the fluid ages much faster. Even the density decreases as much as 4 % at 70 degrees Celsius compared to the density at 15 degrees Celsius. This could be a possible threat to the comfort and performance when riding hard on a Motocross racetrack for a long period of time.
The lifetime of lubricant fluids can be cut with as much as 50 % when increasing the working temperature from 60 degrees Celsius to 70 degrees Celsius.
Water & Particles
All sorts of contamination in a system, caused by a number of reasons, are a potential threat to a lubrication fluid. The most common intruders in the life of a hydraulic fluid are water and air, two major factors in decreasing the efficiency and lowering the potential lifetime. When it comes to water it is impossible to keep an absolute non-moisture environment and all oil products actually contain small portions of water. A common mineral oil contains approximately 100-200 ppm (parts per million) without any affects on the functionality and lifetime of the oil. If the amount of water increases by as little as 100 ppm in an oil product the lifetime is decreased and the efficiency becomes very poor within a short period of time. A result of high water levels in a lubrication fluid is corrosion in the mechanical system. The risk for serious mechanical malfunction is fairly small but a potentially larger threat is the creation of small corrosion particles that can start to float around in the lubricant. These small particles can cause all sorts of problems such as abrasive wear, which is the phenomenon when two surfaces start to wear on each other when particles with the size of 75-100% of the distance between the two surfaces is transported in the lubricant and creates unwanted contact. The other potential threat is erosive wear which is the wear of material when particles hit the surface in high speed when travelling in a fast moving lubricant. When passing corners and narrow passages the small particles can round and shred sharp, optimized designs in a hydraulic system, causing poor efficiency and comfort. Let’s kill a darling for the fun of it… no one can have a look at a lubricant fluid and deem if it is good enough to use. The particles that pose a potential threat to the mechanical system are very small. A sharp eye can spot a particle with the size of approximately 0,04 millimetres in diameter but the really aggressive particles have an average size of 0,025 millimetres in size. As a comparison the average human hair is 0,07 millimetres in diameter. You can of course deem the oil useless if the colour is all wrong but by then the amount of particles has been too high for a long period of time.
Air
The insertion of air into a hydraulic fluid can also cause problems. Air is also soluble in oil, just as water is, and in normal atmospheric pressure the percentage by volume of air is approximately seven. This amount is bound to the oil and causes no problem. The problems tend to appear when the volume of air increases and it starts to separate from the oil in small bubbles. This is often caused by cavitations in a shock absorber on the low-pressure side of the piston when compressing. As soon as air bubbles start to float freely in the hydraulic fluid the risk for cavitation increases and the overall characteristics of the shock absorber becomes very poor.
Bushings and seals
Something that not many may think of is the fact that all seals that separate the oil from the outside environment are potential enemies to the fluid inside the system. The seal can actually absorb the lubrication fluid; causing swelling that makes the suspension system stiff and unsmooth. Swelling is not the only negative thing that can occur; the oil can work the other way around, dissolving the softener that all rubber mixtures contain. This will cause a hard, dry seal that can cause potential leakage.
The difference between oil and oil…
Almost all of you have heard of mineral oil and synthetic oil. But what is really the difference? They certainly have a different price tag when you choose between them in the store. Why is that? Mineral oils are one of the numerous products created when the crude oil from the oil fields is distilled and separated into base products. It all comes down to the sizes of the molecules that are represented in the mix. In mineral oils the amount and sizes of molecules differ a lot and as a result of that the overall performance of the oil can be somewhat unpredictable and varying. The large molecules have a tendency to thicken and the small molecules tend to evaporate when the temperature rises to unwanted levels.
The synthetic oil is produced in a very different way. It is born from a chemically manoeuvred process with mostly ethylene gases as a cornerstone of its compound. The product is often named PAO (Polyalfaolefin). In this process you can actually separate a certain fraction to produce very homogeneous oil with small variations of the molecules inside. In the end the synthetic oils are more precise products that will last for a longer time with a more stable personality, the so called “stay in grade” of the product.
The truth about oils…
When faced with all the potential enemies a lubricant fluid has to fight off and the multitude of areas that Öhlins shock absorbers, front forks and steering dampers work in, you really need a professional lubrication fluid, made from scratch to fit specific purposes. While we are still at it, why not kill another precious darling? When buying motor oil for your car the price tag differs a lot depending on the brand of the lubricant. But within the automotive industry the rules and regulations concerning the recipe for oils are rigorous and the accepted base oils and additives are pinpointed to a very high level of detail. If you want to make motor oil for cars and pass the tests you really have to follow the rules. You can be fairly certain that your car will work just fine no matter what brand you put in, as long as it is classified and suitable for your specific car model. The same thing can not be said about the shock absorber area where absolutely no rules and regulations have been drawn up. This is why a serious suspension manufacturer needs a close cooperation with a lubricant specialist.
Tailor-made oils…
Based on the facts above the lubrication fluids from Öhlins Racing are tailor-made for their products. In close cooperation STATOIL and Öhlins engineers oversee that every drawing is scrutinized for each and every product. Based on the results in combination with the kind of use the shock absorber is tended for, a special lubrication fluid is made to fit like a glove in the system. Just like in Cinderella the shoe will only fit one and no one else and the exact same thing can be applied to the insertion of lubrication fluids into Öhlins suspension products.
As soon as you change to another fluid or brand the functionality, comfort and performance will be compromised and only luck will separate the ones that don’t feel any difference from those that lose their edge when riding on Öhlins suspension. It is not by chance that Öhlins find the optimal hydraulic fluid… up to 150 different oil recipes are tested during the R&D phase to find the perfect match. What are the odds that you will find an identical hydraulic fluid on the shelf in your local store? We know that we don’t know… As in all other sciences things are in constant flux. New materials, optimized designs and new areas of use force all serious suspension manufacturers to keep up with the latest technology. As a result of this never-ending process Öhlins works side by side with STATOIL and Luleå University, where scientists are conducting a number of projects to learn more about the fascinating liquid.
In the end all new findings in the area of lubrication fluids will find their way into the suspension products that you might buy from Öhlins in the future. One thing is for sure. The lubricant in your Öhlins suspension product is made out of devotion, care and great passion.