Issue link: http://read.dmtmag.com/i/859318
Engine Oils Background & Properties castrol.com/GPS 800 255 4417 May 2025 GPS Industry Specifications Hydrocracking, or hydrorefining, is another severe form of hydrogen processing whereby larger, waxy molecules are cut into smaller, lighter weight ones. Hydro de-waxing reduces the wax content and increases pour point. Group II Hydrocracked base stocks contain over 90 percent saturated molecules and typically have VIs of 95 to 115. ey exhibit strong oxidation stability and excellent demulsibility. Castrol uses hydrocracked, Group II base fluids in most of their engine, transmission, hydraulic, and gear oils. Group III base stocks are generally hydro-isomerized during the hydrorefining process, improving the VI to 120 or higher by rearranging the branching of basestock molecules. Group III base stocks also exhibit other improved qualities compared to Group II oils such as reduced volatility and improved oxidation and deposit resistance. A properly balanced additive package is the critical link to bringing out the best performance in a high quality base oil and, ultimately, in the user's equipment. Castrol has been one of the largest users of Group II base stocks for many years. Castrol also focuses on balancing premium-performing additives with base oil for lubricants that exceed manufacturers' recommendations and customer expectations. 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 e 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. e 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 com- bustion 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. e stronger the TBN, the better an oil's acid neutralizing effects. For more information on TBN, see page A-17.. • 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. A22 ecastrof