This presentation contains monograde and mutigrade oils, graphical comparison between monograde and multigrade oils about how viscosity changes with temperature.

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

9. Tarique Ahmed Memon

10. THE END
Tarique Ahmed Memon