Issue link: http://read.dmtmag.com/i/859318
Engine Oils 1 800 255 4417 www.castrol.com/GPS Background & Properties Important Engine Oil Properties July 2017 Additives In today's marketplace, there is very little conventional oil that does not contain additives. Especially prevalent in the heavy-duty industry, diesel engines with high rates of soot and contamination demand a top performing additive package in an engine oil. Generally, additives are used to perform one or more of the following functions within a finished lubricant: • Protect metal surfaces • Extend range of lubricant applicability • Extend lubricant life The different types of additives on the market can be categorized according to functionality as surface protectors, performance oriented, and protection based. A brief overview of the additives within each of these categories gives insight into the benefits of lubricants containing such additives. Surface Protecting Additives Although grouped together under surface protectors, each of the additives below has a very specific job within the finished lubricant. The largest group of additives, surface protectors, can be found in almost every type of lubricant on the market today. • Considered a cleaning agent, detergents prevent deposit formation by either combining with solid combustion debris or changing combustion and oxidation acids into inactive, neutral salts. Total Base Number, or TBN, is a measure of the detergent's ability to neutralize acid. The stronger the TBN, the better an oil's acid neutralizing effects. For more information on TBN, see page A-15. • Dispersants, another cleaning agent, control sludge and varnish by keeping particulates from grouping together to form larger deposits, which become sludge and varnish over time. A lack of dispersants can increase oil viscosity due to the agglomeration of soot and combustion by-products. • Anti-wear agents prevent metal-to-metal contact by adhering to metal surfaces and forming a protective film. Anti-wear agents must be selected carefully because they can affect hydrolytic and frictional stability, as well as become corrosive to yellow metals. • Rust and corrosion inhibitors protect metal surfaces from water-related wear. Improper rust protection can result in significant corrosion in transmission or final drive gear. Rust and corrosion inhibitors protect components by forming a protective layer on the component or by neutralizing harmful acids. • Found primarily in heavy-duty transmission fluids, greases, and gear lubricants, extreme pressure (EP) agents are a special type of anti-wear agent in that they protect against metal-to-metal contact but under extreme loads and temperatures. EP agents must be monitored carefully because they may have compatibility issues with other active chemicals in the lubricant and with yellow metals, such as copper and bronze. Other trade-offs include hydrolytic stability and frictional characteristics. • Friction modifiers work to improve the overall efficiency of a lubricant by decreasing friction, preventing scoring, and reducing wear and noise while adding some fuel economy. A 23