Monograde and multigrade oils
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The document discusses engine oil viscosity classification by the Society of Automotive Engineers (SAE), highlighting the differences between monograde and multigrade oils. Monograde oils are suitable for either winter or summer based on their grades, while multigrade oils function effectively across a range of temperatures. Multigrade oils offer advantages such as reduced wear during startup and potential fuel savings compared to monograde oils.
Monograde and multigrade oils
- 1. Engr. Tarique Ahmed Memon Lecturer @ Department of Mechanical Engineering Quaid-e-Awam University of Engineering, Science & Technology (QUEST) Campus Larkano, Sindh, Pakistan.
- 2. Classification by viscosity • Society of Automotive Engineers (SAE) is an international standard established for the viscosity of engine oil by the SAE. • The SAE classifies oil viscosity with a number. • Viscosity is liquid’s resistance to flow. • The thicker the oil, the higher the viscosity. • The thinner the oil, the lower the viscosity. Tarique Ahmed Memon
- 3. VISCOSITY GRADES OF AN ENGINE OIL • The Society of Automotive Engineers (SAE) has developed a system for classifying oils according to their viscosity grade at low and high temperatures. • Monograde Oils • Multigrade Oils Tarique Ahmed Memon
- 4. Monograde Oils • The grades SAE-XW are only suitable for use in Winter. • Thin oils good for winter use/cold starting. • The ‘summer time’ grades SAE-X are more suited for warmer (or summer time) temperatures or for use in an already hot engine. SAE XW (SAE 5W, 10W, 15W and 20W) SAE X (SAE 20, 30, 40 and 50) Winter Season (Cold) Summer Season (Hot) Tarique Ahmed Memon
- 5. Multigrade Oils • A Multigrade oil meets the requirements of multiple grades. • — one “W” grade and one single grade, e.g., 5W-30 or 15W-40, etc. • This grading system defines the viscosity performance of the oil at both the low-temperature range and the high-temperature range. • Produced by blending a low-viscosity base oil with VI improver additives. Tarique Ahmed Memon
- 6. • The SAE viscosity grade is written as SAE XW Y Low-Temperature Viscosity High-Temperature Viscosity Tarique Ahmed Memon
- 7. SAE 10W-30 Multigrade Oil behaves; Cold: like an SAE 10W monograde oil and Hot: like SAE 30 monograde oil Tarique Ahmed Memon
- 8. Advantages of Multigrade over Monograde Oils • All the engine oils drops back in crankcase when an engine is at rest. • When the vehicle starts again, the oil needs a certain time (a few microseconds) to reach and lubricate the different parts of the engine. • Since a multigrade oil is more fluid at low temperatures, it will reach all the engine components faster than a monograde oil, thereby reducing wear at start-up. • Using multigrade oils can result in fuel savings of 1.5% to 3% compared to monograde oils. • A multigrade oil offers better engine protection at low and high temperature as it maintains optimum viscosity across the whole engine operating temperature range. • Engine’s capacity to start, at low temperatures. • The smaller the number, the easier it is for the engine to start cold. Tarique Ahmed Memon
- 10. THE END Tarique Ahmed Memon