MOTUL
SCHOOL
CHOOSING VISCOSITY GRADES
For Your Car
Developing & distributing the highest
quality performance lubricants since 1853.
Most oils these days are “Multigrades”, which
simply means that the oil falls into 2 viscosity
grades as shown by the numbers on the bottle.
They were developed some 50 years ago to
avoid the routine of using a thinner oil in winter
and a thicker oil in summer.
Understanding Viscosity Grades
You will probably recognise these numbers on a bottle of oil, they are
known as viscosity grades. Viscosity is the measurement of a fluids
resistance to flow.
Viscosity grades essentially let you know what temperatures the oil can
handle.
- Like how thick your oil is at its normal operating temperature,
- Or how cold it can get before your oil stops flowing,
- And how thin your oil is at hot temperatures.
Reading Multgrades
Understanding the numbers
Multigrade Oil
-
Winter Grade ‘W’
-
-
-
Summer Grade
-
Maintains the lubricant viscosity over extreme
temperatures.
Therefore giving your engine protection across a wide
temperature range.
The ‘W’ stands for ‘Winter’.
The lower the number infront of the ‘W’, the lower the
temperature the oil will remain liquid.
It tells you the thickness of the oil and the absolute lowest
temperature the oil will remain liquid in.
Indicates the thickness of the oil at operating temperatures.
This is important to know for those hot days when sitting in
traffic.
Viscosity Index Improver
Clear Polymer
How can the same oil work when it’s
really cold and really hot?
By adding a clear polymer powder to the oil
known as a Viscosity Index Improver.
The polymer expands as the oil gets hot,
making the oil thicker.
The Right Oil Changes Everything
Choosing the right multigrade engine oil makes all
the difference. The 3 key areas of benefit are;
For Australia, where we regularly see 35deg C days in summer, having
the right hot viscosity grade is essential for extending the engine life. The
most common reason for oil to break down and damage your engine is
excessive heat or inability to handle heat.
MOTUL School
Choosing Viscosity Grades