Additives
Extreme Pressure (EP) Agents: EP agents increase the load carrying ability or film strength of lubes. This in turn prevents or at least minimizes direct metal-to-metal contact. Many gear systems need lubes fortified with EP agents to function properly. Some EP agents include sulfurized sperm oils and Molybdenum disulfide.
Anti-Corrosives: These materials prevent chemical corrosion from occurring. They can accomplish this by forming a chemical, protective coating on metal surfaces, or they can directly attack and neutralize materials that usually cause corrosion.
Viscosity index (VI) Improvers: VI improvers consist of polymers whose properties change significantly with temperature such that a lubricant resists "thinning out" as its temperature increases. Polyisobutylenes were among the early compounds used. The latest technology uses copolymer chemistry, which seems to be far more stable, particularly for use in diesel engines. A VI improvers function is to enable much improved cold starting capabilities while retaining necessary film thickness at operating temperatures
Pour Point Depressants: The pour point of a lube is simply the temperature at which it no longer pours. The amount of wax in a lube influences its pour point. Pour point depressants minimize the size of wax crystals formed in the lube. By so doing they allow the lubricant to achieve its lowest possible pour point, based on Its true viscosity characteristics and not on its wax content. Polymethacrylates are the general class of organic compounds used as pour point depressants, also providing some VI improvement.
Other Metals: There are a number of other metals that are used as additives Molybdenum (Mo) as Molybdenum disulfide is a solid lubricant used as a friction reducer or TP agent in certain specialty lubes. Levels of nearly 1 % (l0,000 ppm) are not unusual. Boron tends to be found co-existing with Mg additives at up to 4% of the Mg value. Similarly, sodium may be found in the presence of Ca or Ba.
