Issue link: http://read.dmtmag.com/i/859318
Engine Oils Background & Properties castrol.com/GPS 800 255 4417 May 2025 GPS Industry Specifications Pour point is a relatively crude measure of cold temperature performance and should not be used as the sole indicator of a fluid's cold temperature properties. It should be viewed in conjunction with more precise testing methods such as pumpability via TP-1 coding, D-4684 and end Brookfield viscosity measurements. Demulsibility e ability of an oil to separate from water that has contaminated a system is called "demulsification." A lubricant's ability to separate from water is a necessity for applications where water can attack metal parts or even cause additives to drop out of the finished lubricant. Demulsibility is especially important in hydraulic fluids. Oxidation Chemically, oxidation occurs when hydrocarbon molecules react with oxygen molecules at elevated temperatures. An oxidized oil thickens excessively, jeopardizing pumpability to critical parts, and can become acidic and eventually corrode metal surfaces. Good oxidation performance in a base oil relates directly to how "saturated" the base oil is. Saturation refers to the amount of base oil molecules that have no chemically active double bonds. is creates a situation where there is less chance for oxygen to bond with any molecules, which would eventually lead to oxidation. Mineral base oils treated during refining with hydrogen are more saturated, and therefore have better oxidation stability than mineral base oils not treated with hydrogen. H H H H H H Non-Saturated Base Oil Oxidized Oil C C C C H H C C H H – – – – – = = O H H H C C C C H H C C H – – – – – – – = O = O = O = H H H C C C C H H C C H H H H H H H – – – – – – – H H Saturated Base Oil ermal Stability Base oils that can withstand high temperatures for long time periods without oxidizing are termed "thermally stable." In applications that experience high operating temperatures for extended lengths of time, thermal stability cannot be compromised. ermal stability is achieved by good base stocks and additives. Base Oil Groups ere are several major types of base oil groupings. Each base oil group has specific characteristics that relate to the application of the finished lubricant. As illustrated, progressing from aromatics up to synthetic base oils increases the oxidative stability, viscosity index and amount of saturation typically found in the base oil. It is important to note that these base stocks are not always interchangeable. Additive packages that produce approval with Group I base stocks in finished lubricants may not replicate that approval in a Group II A19 Oxygen can easily attach to available carbon molecules Oxygen has reacted with available carbon and oxidation occurs No oxygen can attach because oil is 11 saturated'' with hydrogen ecastrof