Lubricants provide three major functions within your engine: cooling, cleaning and reducing friction. The goal is to protect the engine components against damage from heat, contaminants and metal-to-metal contact. But how exactly does the engine oil accomplish these things?
The lubricant consists of the base oil, an additive package and viscosity modifier. The base oil alone isn’t enough to provide a full-range of protection. It’s the additives, base oil, and viscosity modifier together that do the work. And the careful formulation of these additives can address each potential threat to your engine, giving years of trouble-free and efficient service throughout its life.
Controlling Corrosion and Acids
Engine corrosion occurs when acids builds up in the lubricant. Acids can cause major damage and a reduction in performance. If your engine parts start to corrode from acids, it could lead to engine failure. These acids can be neutralized by a detergent. The detergents protect against damaging rust, especially on the bearings. Detergents deliver base to help protect against acid corrosion. In addition some high-performance formulations may carry corrosion inhibitors to further protect soft metals.
Soot and sludge are byproducts of combustion. If the lubricant is untreated, both soot and sludge can build grow and accumulate in the oil block oil passage and collect onto essential engine components. Adding a dispersant can keep soot and sludge particles from forming large deposits and causing problems.
Heat and oxidation can cause lubricants to breakdown. When oil breaks down in an engine, large deposits can form on the surface pistons and oil passages which can prevent engine parts from functioning as intended. Additives work to prevent oxidation and clean engine parts to prevent and stop depositing from forming.
Reducing Engine Wear
There’s no way to completely eliminate engine friction–we have to manage it. Unmanaged friction causes a heat buildup and engine wear. The additive solution is an anti-wear agent that forms a solid film on metal surfaces. This protection prevents damage from all types of friction. Friction modifiers can be added to further protect surfaces from the damage of friction.
Friction and combustion naturally cause heat. Heat can damage parts, and reduce the ability of the other additive components to work properly. One way that heat negatively affects the engine lubricant is through increased oxidation. As oxidation occurs, sludge can build up in the oil. The viscosity (or thickness) increases, and the likelihood for deposits also increases. To prevent oxidation and all of its resulting dangers, an additive package should include antioxidants. Because heavy duty engines tend to run hotter, it’s even more important that the antioxidants do their job to keep the oil free from soot and sludge.
Keeping the lubricant’s viscosity consistent is key to making sure that all the components work together. Shear stability is a measure of how well the oil maintains its original viscosity. If the lubricant changes in viscosity during normal operation, you can lose pumpability and durability. Heavy duty diesel engines put an incredible amount of load and stress on the lubricant, making the shear stability critical. Viscosity modifiers help maintain viscosity through changes in temperature. If the viscosity breaks down, the engine parts are at risk for major damage.
At low temperatures, the wax in base oils separates and forms crystals that interlock and prevent oil flow. Pour point depressant additives modify the shape of wax crystals to prevent them from interlocking, enabling the lubricant to pour at extreme low temperatures.
When air gets into the lubricant, it can cause loss of power and loss of pressure in the sump. Foam in a lubricant will not allow the fluid to do its job of protecting critical moving parts. Cavitation caused by aeration can cause catastrophic engine failure. Foam inhibitors can minimize these problems.
Industry Demands More Functionality
The move to more stringent durability and performance standards is being seen across many parts of the globe. Higher performing engine lubricants have a vital role to play, delivering the durability and performance standards that vehicles require; protecting against engine wear, damage, and corrosion while playing an ever greater role in fuel economy and emissions reductions.