Issue link: http://read.dmtmag.com/i/859318
Hydraulic Fluids Background & Properties castrol.com/GPS 800 255 4417 May 2025 GPS Important Anti-wear Hydraulic Fluid Properties Synthetic Group III Refined Group III base oils are petroleum fluids that undergo extreme refining techniques that produce a base fluid with characteristics similar to a man-made synthetic. Group III refined base oils are typically found in partial to full synthetic finished lubricants since they have greater than 90% saturates (usually 99%+) and VIs over 120. ey have low pour points, good oxidation resistance and can solubilize additive systems better than their man-made counterparts. Synthetic PAO Group IV Group IV base oils are known as polyalphaolefins (PAO). PAOs, the most widely used of the engineered base stocks, consist of all saturated hydrocarbon structures and contain no unwanted sulfur or other metals. Free of wax, PAOs enjoy very low pour points and have VIs typically of 140. PAOs have good thermal stability but are sometimes difficult to blend with additives. Despite their noted performance features, PAOs are sometimes cost prohibitive for users. Group V: All Others Group V base fluids consist of "all others," predominately esters and polyolesters, along with aromatic and naphthenic. • Aromatic base oils are not suitable for use in heavy-duty lubricants due to their poor oxidation stability and low VIs of 0 to 45. Aromatics also contain elevated levels of sulfur (which leads to deposit formation) and sometimes nitrogen (which contributes to oxidation and deposit formation). Aromatics are typically used as solvents, cleaners and process oils, and in further chemical reactions for industrial products. • Naphthenic fluids have low to medium VIs of up to 60 typically and they exhibit very low pour points, high solubility and excellent cold flow in long term storage. Group V base fluids are commonly used in refrigeration lubricants, metalworking oils, greases and as extreme cold temperature fluids, such as snowplow oils. ese include: Vegetable Oils Vegetable oils are derived from plants with the most common being canola oil. Vegetable oils are esters of fatty (long chain) acids and are about as stable as group I mineral oils. e most desirable property of these oils is that they are environmentally friendly in three ways: 1. e process to create the oil is growing a plant. 2. e oils themselves are non-toxic and, in some cases, edible (canola oil's biggest use is salad oil), but including additives to make a suitable lubricant increases the toxicity. 3. Vegetable oils are 100% biodegradable. (However, the oil plus additives are less than 100% as most of the additives will not readily biodegrade.) C11 ecastrof