BIZOL Additives – from standard to excellence
A high VI means that synthetic oil retains its viscosity when exceptional hot or cold. Synthetic oil generally has a lower pour point, therefor needs lower levels of pour point depressants than conventional oils which have high levels of waxes that solidify at low temperatures. The lower level of aromatics also benefits the oil as lower levels of sludge dispersants are required. One additive that is necessary is a seal conditioner to ensure seals retain their elasticity and do not dry out. Additives are also needed to disperse products of combustion such as soot. Overall, the additive package requirements are vastly reduced and synthetic oils are suitable for long service life. The additive spectrum is divided into three main categories, depending on the mechanism of action. The surface-active additives protect or improve the surfaces of the metal parts of the engine. The oil preserving additives optimize the aging characteristics of the oil and serve as an enhancer for the operating time of the lubricant. And last but not least the oil improving additives stabilize or augment the present features of the oil and support the quality and performance levels.
Surface Active Additives
Detergents – washing-active substances and alkaline reserve
At high temperatures deposits of the oil, like varnish and oil carbon, can appear and contaminate the engine and tend to congregate at hot spots (e.g. piston area). To prevent such problems, detergents are blended within the oil. This additive hampers the adhesion of deposit molecules to the metal surfaces of the engine. Simultaneously they are able to inactivate acids to prevent corrosion. The measure of acid neutralization capability is shown with the TBN (Total Base Number). The higher the value (mg KOH, potash lye – potassium hydroxide – per gram of sample), the more volume of acids can be neutralized. The process of neutralization consumes the potassium hydroxide inside the detergents and the TBN lowers over the time. A good indicator for a possible oil change, simply measured with the help of titration.
Dispersants – floating dirt particles
To prevent coagulation of self-sticking, cohesive impurities and deposits dispersants are used to keep the particles floating. The additive coats the very small particles with emulsifying molecules. One part is lipophilic (“fat loving”), the other is hydrophilic (“water loving”) and the disposition of the impurities to dissolve in oil is increased by adapting between these different solubility characteristics.
Anti-wear (AW), Extreme Pressure (EP) – pressure resistant lubricating film
Under high pressure and in case of increased load the metal surfaces of moving parts can come so close that in microscopic dimensions the uneven areas get in touch. The colliding concavities are leading to destruction or even wielding-like effects of the surfaces and the metal is damaged irreparably. Exposed areas are especially the camshaft, gear flanks and bearings. “Anti-wear” or “Extreme Pressure” additives form a protective film on these surfaces which is able to withstand extreme mechanical stress and thus the oil film is not interrupted. More than ever, stress-acceptance of the additives is claimed from the industry. This leads to the use of Sulphur-phosphorus based extreme pressure (EP) chemicals. The EP additives create organic- metallic crystals on the affected surfaces that are used as sacrificial layers to protect against abrasive surface damages. There are two main types of EP additives, those that are temperature-related and those that are not. The most commonly temperature-dependent varieties include chlorine, boron, phosphorus and Sulphur.
They are activated by reacting with the metal surface when the temperature increases, due to the extreme pressure. The chemical reaction between the additive and metal surface is supported by the heat produced from contact friction. Zinc dialkyldithiophosphate (ZDDP) is a formerly often used EP chemical. Again, the reaction layer provides sacrificial surface protection and is worn off before the metal. Today, legal limitations lower the part of ZDDP in Motor Oils and substitutes are used. ZDDP poisons exhaust aftertreatment systems and interferes with optimal reduction of pollutants. A special problem for older and highly loaded cars (like Rally vehicles), which sometimes need special historic Motor Oil lines or ZDDP additives.
Corrosion Inhibitors (CI) – water-repellent coating
Oxygen, water, and other aggressive combustion by-products lead to corrosion of the metal parts of the engine. Corrosion inhibitors build up a “fur-like” and water-repellent coating on these surfaces. Due to that, the aggressive chemicals cannot come in touch with these important areas and the performance quality of the engine is preserved.
Friction Modifiers (FM) –optimum friction values
Synchronized gearboxes, automated transmissions, limited slip differentials, and wet brakes need special friction values of the lubricant in order to function properly. With friction modifiers the exact traction is achieved and the transmission of movement and / or torque between these metal pairings is guaranteed.
Oil Preserving Additives
Anti-oxidants (AO) – longer engine oil life
AOs serve as a preventive anti-aging component. They chemically suppress oxidative reactions inside the oil which is likely to oxidize, when exposed to heat and oxygen. Darkening discoloration, blurring, and oil thickening appear when aging takes effect. Aged oil must be drained and interchanged with fresh oil.
Anti-foam (AF) – less oxidation, better pressure resistance
Intensive turbulences caused by stirring and whirling of the oil bind air inside the lubricant and foam are generated. By manipulating the surface tension of the oil, the trapped air will be released and the foam layer decreases respectively does not develop. As mentioned before, oxygen is a molecule responsible for oil aging and keeping it outside the oil is mandatory.
Viscosity Modifier (VM) – small deviations over a wide temperature range
A good lubricant provides excellent flowability at cold ambient temperatures as well as under hot circumstances. To be able to show this feature, the oil needs viscosity modifiers and, in fact, to increase the viscosity index value. With these polymers mineral oils can become multigrade oils and the VI of synthetic oils can be improved or at least maintained. VMs consist of very large, thread-like hydro-carbons which are spatially small at cold temperatures, but extend and widen when it gets warmer. They can be sheared and destroyed because of their size and attention to the engine system must be paid if VMs are suitable for this precise application.
Pour Point Depressant (PPD) – low point temperature appropriate
At very cold temperatures mineral oil tends to crystallize and harden. The paraffin inside the oil is discharged and interacts; the phase of the oil is negatively influenced. Pour point depressants cannot prevent the crystallization, but they inhibit the growing and the interconnection of the wax crystals. The oil stays liquid and can be used till -49 °C (-56 °F) on an average with specific fully synthetic blends.
Seal Swell Agents (SSA) – tightness through swelling
Specific synthetic hydrocarbons (PAOs) can dry out the seals inside an engine and they would shrink and become brittle. The sealing effect is not guaranteed anymore and while operating the engine could get severely damaged. To save the elastomers from drying out, SSAs protect specifically these kinds of plastics and help preserving the integrity of the seals by swelling the sealing device.