Issue link: http://read.dmtmag.com/i/859318
Greases Background & Properties castrol.com/GPS 800 255 4417 May 2025 GPS General Information When heavy-duty equipment requires a lubricant that has staying power, thickness and the ability to provide a seal between moving parts, a grease is typically recommended. e National Lubricating Grease Institute (NLGI) defines grease as: "A solid to semi-solid dispersion of a thickening agent in a liquid lubricant. Additives imparting special properties may be included." is means that grease is mainly base oil plus soap or thickener and additives. Each of these grease components is reviewed in depth below: ickeners Grease is usually identified by the type of thickener or soap used in its formulation. Each thickener has several inherent characteristics that enhance the finished grease product. e following is an explanation of the most common grease thickeners and their properties. Note: e temperatures quoted below represent the suggested maximum service temperature for each type of thickener. is is not the same as the thickener's dropping point, which is, on average, 100°F higher. In practice, upper end service temperatures are limited by flash point and oxidation of base oil. • Sodium Soap: A fibrous thickener that provides natural rust resistance but has poor water resistance. It is generally associated with poor low temperature properties. A sodium soap is recommended for use in a maximum temperature range of 200-275°F. is thickener is basically obsolete. • Calcium Soap (Simple): Calcium soap is known for its smooth structure and excellent water resistance. Its maximum service temperature is 250°F. • Calcium Soap (Complex): Calcium complex is still smooth in texture but contains inherent extreme pressure load-carrying abilities and good water resistance. Its maximum service temperature is 300°F. • Calcium Sulfonate: is thickener is noted for its excellent rust protection and service temperature that tops 400°F. Its texture is smooth. • Lithium Soap (Simple): Another smooth-textured thickener, a lithium soap boasts good water resistance and mechanical stability. Its maximum service temperature is 325°F. • Lithium Soap (Complex): Like its simple counterpart, lithium complex soap has good water resistance and mechanical stability but a higher service temperature of 400+°F. Its texture is smooth but slightly stringy. • Aluminum Complex: A smooth gel with excellent water resistance, shear stability and pumpability. Its maxi- mum service temperature is 400+°F. • Clay: A smooth-structured thickener known for its ability to resist melting and excellent water resistance. • Polyurea: An opaque, slightly mealy thickener, Polyurea has good oxidation and water resistance. Its maxi- mum service temperature is 350°F. F2