Automobiles regularly require oil to run properly. This is because engines contain many parts that rub against each other and create friction. This friction causes heat, which can damage the engine of a car. Oil works as a lubricant between the parts and reduces the amount of heat produced. Over time, however, oil breaks down and needs to be replaced.
The main ingredient in oil is a large molecule called polyethylene – this is where we get its name from: poly-ethylene glycol – or PEG for short. A new and improved form of PEG has been developed over recent years: it’s called silica-coated PEG (S-PEG). Silica coating helps leng life by protecting the polyethylene molecule from acidic conditions within the engine.
The production of this silica-coated PEG is now so advanced that it can be used as an ingredient in oil to produce self-lubricating oils . It works by coating the metallic surfaces inside the engine, preventing them from reacting with each other and reducing friction. This way, heat levels are kept low, which leads to a longer life for your car parts.
WHAT DOES MOTOR OIL REALLY DO?
Oil has several important functions. Oil acts to prevent excessive wear of moving parts, provides cooling for internal engine components, seals in the oil film during periods of little or no motion, and removes heat from friction points.
OIL DEPLETION PROCESS
When motor oil is placed under shear stress (i.e., when one surface moves across another), including when rotating parts are forced to turn against each other by the engines rotation, small particles break away from the fluid base. This process is known as shearing or thinning out. The thinner the mixture of oil becomes, the greater will be its ability to lubricate between metal surfaces that rub together. A certain amount of thinning is necessary for proper lubrication; too thick and there will be no lubrication and metal-to-metal contact.
OIL THICKENING PROCESS
In the absence of oil, a thin film of moisture from atmospheric humidity naturally forms on surfaces. The presence of motor oil, however, prevents this natural process from occurring by absorbing moisture out of the air and into the oil. This is important because water is corrosive to metal parts when in liquid form or in the form of steam between moving parts that rub against each other. Water breaks down motor oil’s base chemistry resulting in varnish, sludge and corrosion which shortens equipment life through subsequent loss in viscosity (thinning), high temperatures created by friction and acid formation, plus an increase in wear. Moisture is an enemy to be conquered.
OIL PROTECTION PROCESS
While oil is a great water-absorbing agent, it also acts as a barrier between metal parts that rub together. The three basic functions of lubrication are:
The first two functions, prevention of excessive wear and heat transfer, require no explanation. But how does oil prevent corrosion from taking place? Oil’s alkaline base neutralizes the acid formed by contact with moist air through a reaction process called saponification or soap formation. In this process of breaking down under the influence of water and certain metals in the presence of extreme heat, the soap compound coats all internal surfaces with a thick layer of protection against both hot metal and corrosive attack.
Oil is not a corrosive detergent. If oil consists of small particles in the fluid base, then they will adhere to moving metal surfaces and this provides protection against wear by filling in irregularities or asperities (high points) on mating parts. Oil also acts like a sponge when it comes in contact with water; it absorbs the moisture and carries it to the engine sump where it can be disposed of through the regular oil change process.
OIL FILM THICKNESS
The alkaline saponification process continues until enough water has been turned into soap to thicken the resulting oil mixture to what is known as its “boundary” state, at which point no more can be absorbed into that particular quantity of oil. The thickness of the resulting oil film is dependent upon the amount of soap formation, which in turn depends on the amount of water that has been absorbed into the oil mixture. For example, if there is very little water present in an engine lubricant system, no soap will be formed and therefore only a small amount of thickening will take place.
OIL FILM STRENGTH
The strength or thickness of this film between metal parts is known as its “film strength.” A strong film provides good wear protection while a weak film results in increased friction and heat (which reduces power), plus accelerated component wear due to lack of protection against corrosion (rusting). While it seems logical that any oil should provide some degree of protection under these circumstances, the truth is that not all motor oils are equal when it comes to their ability to maintain a strong oil film between metal surfaces in moist or water-laden atmospheres.
In order for oil to maintain its alkaline properties indefinitely in a humid atmosphere, it must remain in a chemically active condition at all times. This is accomplished by using a base stock chemistry that has been properly formulated with the proper additives and then blended into the finished product in the correct quantities. Under certain operating conditions, however, oil can break down into components which adversely affect its ability to protect equipment from attack by moisture and corrosive acids formed when water contacts hot metal surfaces. One such additive known as zinc dithiophosphate (ZDDP) is extremely important in achieving this result. ZDDP has been added to motor oil for many years and its addition has, up until recently, been relatively simple because it was the only anti-wear additive used in lubricating oils.
PROBLEMS IN BLENDING OIL ADDITIVES
In recent years a number of new additives have come on the market that do more than just prevent wear; they claim to clean out deposits from engine oil passages, increase viscosity index (VI) values, and improve fuel economy – all at one time. To meet this challenge, motor oil manufacturers must find a way to blend these additives into their base stocks without destroying the integrity of other additives already formulated into the finished product or seriously affecting the life-extending chemistry of ZDDP.
A problem that motor oil manufacturers face in trying to meet these challenges is additive stability – keeping additives in a fluid base stock without separating out into layers during storage or use. This situation can result when an additive chemically reacts with another component of the oil, either with itself, another additive or even the base stock, forming one or more low-viscosity layers which settle out of suspension and tend to concentrate at the top of the reservoir where they continue to react until there is nothing left in the lower portion but wasted product. Oil formulations for special applications often contain so many ingredients in such small quantities that it is difficult for manufacturers to blend them into finished products and maintain stability. Such products may also tend to separate out on standing.
Oil manufacturers must be able to blend additives into finished oil without destroying the integrity of other ingredients already formulated in the product and especially not affect the anti-wear chemistry of ZDDP which is critical for protecting equipment operating in moist atmospheres such as found beneath crankcase breathers or in areas containing an abundance of water such as around water jackets, engine cooling systems and transmissions.