31Manufacture of Lubricating Oil
or mixed-base crude oils. The main functions of lubricating oil include reducing
friction, carrying away heat, protecting against rust, protecting against wear, and
removing contaminants from the engine. Additives are used to enhance the natu-
ral properties of the lubricating oil and to prevent undesirable properties (Rudnick
2009).
Thus, additives are chemical compounds added to lubricating oils to impart spe-
cic properties to the nished oils (Ludema 1996; Leslie 2003; Rizvi 2009; Ahmed
and Nassar 2011). Some additives impart new and useful properties to the lubricant,
some enhance properties already present, whereas some additives act to reduce the
rate at which undesirable changes take place in the product ...