UNDERSTANDING ENGINE OILS OIL FUNCTIONS BASE OILS LUBRICATE PARTS and PREVENT WEAR: All Oils Are Made up of Base Oils and Additives
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UNDERSTANDING ENGINE OILS OIL FUNCTIONS BASE OILS LUBRICATE PARTS AND PREVENT WEAR: All oils are made up of base oils and additives. Not all This is the basic function of all oils. Keeping the moving base oils are created equally however. The API classifies parts separated. In general, the thicker the oil film, the these into 5 main groups. better the wear protection, but the oil additives also Sulphur Saturates Manufacturing Group VI play an important role. Modern oil additives allow an oil % % Method of lesser viscosity to be used and still provide the same I >0.03 <90 80-119 Solvent Refined level of protection. II <0.03 <90 80-119 Hydro-processed REDUCE FRICTION: Severely hydro- The film of oil reduces friction simply because there is III <0.03 <90 120 + processed Understanding Engine Oils Understanding no metal-to-metal contact. The heavier the oil though, Poly Alpha Olefins Oligomerization | IV the greater the drag and hence more heat may be (PAOs) (man made) generated. Correct oil selection is therefore a balance All Others V Various between what is needed to protect the component (including esters) without generating excessive drag and heat, thereby Group III and IV base oils are 100% synthetic. Some very decreasing fuel economy. high quality Group II oils (called Group II Plus) are PROTECT AGAINST RUST AND CORROSION: also accepted as having synthetic performance. When As oils degrade, they form corrosive by-products so the looking at the table, think of saturates (relates to ENGINE OILS oil contains anti-corrosion and acid neutralising additives aromatics and other hydrocarbon molecules) and sulphur to protect components against rust and corrosion. levels as the degree of purity of the oil. The Group III products used by Penrite are over 99% pure. PAOs BE COMPATIBLE WITH SEALS: are even more pure than Group III oils. Group I and II Oils must lubricate and not cause deterioration, shrinking base oils are considered mineral. or hardening of commonly used seals. Synthetic base oils are used for two main reasons; PREVENT FOAM: greater oxidation stability (for longer oil life) and low volatility (to decrease oil consumption). In order to meet Foam reduces the lubrication properties of the oil, the ACEA specifications on oil volatility, many lighter therefore oils must be resistant to foaming or be able engine oil viscosity grades must use a percentage of to “release” or “dissipate” any foam quickly. these products, especially if Group I base oils are used. PERMIT EASY STARTING: Group V contains all other base oil types not included Most wear occurs in an engine at start up. Therefore, in Groups I, II, III and IV e.g. Esters, Naphthenics. the oil must have the correct low temperature viscosity to flow quickly to the bearings and valve train to prevent From a Penrite perspective, we choose the combination wear. Some engines require a low viscosity oil to actually of the above base oils to ensure maximum performance start at all, especially some of the new diesel engines for a given oil. found in four wheel drives, where the oil is used to operate the pump to prime the fuel injectors. COOL THE ENGINE: At least 40% of the engine is cooled by the oil, not the Hydroprocessed Based Oils – What do they look like? radiator system. This means the oil is always under heat Group II: stress (oxidation) as it transfers heat from hot spots back to the sump. This includes main and big end • 400°C • >500 psi H • Removes sulphur and nitrogen bearings, the crankshaft, connecting rods, other bearings, • Converts aromatic hydrocarbons to cycloparaffins C C C C pistons and the timing gear. C C C C C C C C C C C C REDUCE COMBUSTION CHAMBER DEPOSITS: C C C C C C C C Some oil will always reach the combustion chamber C C C C either via the cylinder walls or via the valves. It is then C AROMATICS C CYCLOPARAFFINS burned off with the fuel. It therefore must burn clean Group III: enough that it does not build up on valve seats or • 425-430°C • 1,500-3,000 psi H pistons tops which can cause problems. • Converts cycloparaffins to paraffin chains KEEP ENGINE COMPONENTS CLEAN: C C C C C C Oils need to be very stable under heat and not cause C C C C C C C C C system deposits. They also have the added responsibilty C C C C C C C C C of keeping internal surfaces clean and to prevent sludge. C C C C C This is achieved by a combination of detergent and C CYCLOPARAFFINS PARAFFINS dispersant additives. Visit our website at www.penriteoil.com SYNTHETIC BASE OILS: DETERGENTS: ENGINE OILS Any oil with an API engine rating of SC (see page 16 PETRO-CHEMICAL for API Service Classifications), or above has a level MANUFACTURED TYPES of detergency. This detergency level is not necessarily related to all of the quoted API ratings of the oil, as some PAOs – Poly Alpha Olefins: high detergent diesel oils may only meet lower petrol PAOs are derived from the oligomerization, usually of engine oil specifications. It is a balance. Detergents are 1-decene. Oligomerization refers to a process where a usually metallic compounds and they control deposits | monomer or a molecule is linked to many others of and keep engines clean. the same type to form a long chain. Engine Oils Understanding DISPERSANTS: 1-decene is further derived from the oligomerization These are usually ashless (non metallic) organic chemicals. of high purity ethylene (C H ). 2 4 They keep contaminants and by-products dispersed in PAOs are extremely pure: the oil helping to prevent deposits and sludge from • Identical molecules. • No sulphur or phosphorus. • No wax. forming. They are highly effective in controlling low temperature contaminants. They can keep them so Benefits of PAOs: fine in suspension, they pass through the oil filter with • Excellent cold flow properties. the oil additives! • Highly resistant to thermal breakdown. FRICTION MODIFIERS: • Excellent shear stability. Used to reduce internal engine friction and are common in low viscosity oils where fuel economy is important. ESTERS: Manufactured by reacting an acid and an alcohol to OXIDATION INHIBITORS: give ester plus water. There are many types of esters, Reduce oxygen attack or oxidation of the oil, helping to such as diesters and polyolesters. reduce oil thickening, especially at high temperatures. Benefits of Esters: ANTI-WEAR AGENTS: • Resistant to thermal breakdown. Prevent wear due to seizure or scuffing of metal surfaces that would otherwise rub or contact each other. They are • Good metal-wetting ability. normally zinc and phosphorus or other organo-metallic • High film strength. based compounds. • Good shear stability. RUST AND CORROSION INHIBITORS: Prevent rust and corrosion attack on metal surfaces OIL COMPOSITION from acids that can build up in oils. ADDITIVE PACKAGE 8% - 15% FOAM DEPRESSANTS/AIR RELEASE AGENTS: Prevent foam from forming, thereby maintaining a OIL PACKAGE: lubricating film based on oil not air bubbles, resulting VI IMPROVERS / PPD EXAMPLE 5% - 10% in the ability of the oil to be pumped effectively at the required rate. POUR POINT DEPRESSANTS (PPD): Reduce the oils tendency to crystallise at very low temperatures, i.e. Its ability to pour or flow. Most oils BASE OIL 75% - 95% contain wax and, at very low temperatures, wax can crystallize. PPDs assist to lower the temperature at which this occurs. VISCOSITY INDEX IMPROVERS (VII): These change the oils rate of thinning or its Viscosity Different oils require different percentages of additive Index (VI). The higher the VI, the lower the rate of thinning package depending on viscosity grade, specification, of the oil with increase in temperature. They are polymers oil type etc. that expand as temperature increases – think of them as like a slowly uncoiling spring. They also assist in OIL ADDITIVES making oils into multigrades (see page 15). There are different types of oils and they use many of the same types of ingredients. However, these are put together a little differently. Not all of these are found in every oil. Firstly you have base oils, made from either crude oil at a refinery or man-made (synthetics). To achieve the functions required by finished lubricants, you must then put additives in the oil. These all do different things. Visit our website at www.penriteoil.com OIL ADDITIVE PACKAGE UNDERSTANDING VISCOSITIES MOTOR OIL ADDITIVE PACKAGE: EXAMPLE The number in front of the “W” signifies the viscosity DETERGENT of the oil at cold/start up temperature (tested at -10 21% DISPERSANT to -35°C depending on the grade). The lower the first 60% number, the faster the oil flows (pump ability) when the engine is cold. ANTI WEAR The second number represents the oil’s thickness at AGENT 10% operating temperature (100°C). All oils thin out as they get hotter. So, the higher the second number, the less the oil will thin out as it heats up, compared to an oil with a lower second number. 5W-40 10W-40 10W-50 OTHER FRICTION -30oC Understanding Engine Oils Understanding 10W-40 MODIFIER | (ANTI RUST, 10W ANTI FOAM) 4% 15W-40 1% POUR POINT OXIDATION -25oC DEPRESSANT INHIBITOR 1% 3% -20oC Depending on the oil type and specification, the VISCOSITY performance pack will alter significantly. VISCOSITY 40oC 100oC -25oC 40oC 100oC SAE VISCOSITY 5W-40, 10W-40 & 15W-40 10W-40 & 10W-50 have the ENGINE OILS have the same operating same start up viscosities SAE stands for Society of Automotive Engineers. The temperature and different and different operating SAE developed a classification system to define the start up viscosities.