Engine Oil
Jason Dearden
Steven Lemos
Engineering 45
Santa Rosa Junior College
Spring 2009
What Is Engine Grade Oil
American Petroleum Institute (API)
 Society of Automotive Engineers (SAE)

A Brief History of Motor Oil
1846 Crude oil refining process discovered
Single Grade oil
Multi Grade oil
Synthetic oil first sold commercially in 1970
Properties

Physical
Flash Point
Pour Point
Viscosity

Chemical
Basic properties
Detergents
Viscosity



Viscosity is the
measure of a fluids
resistance to flow
How to measure
viscosity
Units:
Dynamic: Pa-s,
Kinematic: Stokes (St)
Dynamic Viscosity
 Kinematic Viscosity
Density
Viscosities of common fluids:
(At 25°C)
Viscosity (Pa·s)
Viscosity (cPoise)
acetone
3.06 × 10−4
0.306
benzene
6.04 × 10−4
0.604
3–4 × 10−3
3–4
blood (37 °C)
castor oil
corn syrup
ethanol
ethylene glycol
glycerol
HFO-380
0.985
985
1.3806
1380.6
1.074 × 10−3
1.074
1.61 × 10−2
16.1
1.5
1500
2.022
2022
mercury
1.526 × 10−3
1.526
methanol
5.44 × 10−4
0.544
1.863 × 10−3
1.863
1.58 × 10−4
0.158
1.945 × 10−3
1.945
nitrobenzene
liquid nitrogen @ 77K
propanol
olive oil
0.081
81
2.3 × 108
2.3 × 1011
sulfuric acid
2.42 × 10−2
24.2
water
8.94 × 10−4
0.894
pitch
Single Grade oil Viscosity
Multi Grade Oil viscosity index improvers
(VII)
CCS=Cold Cranking
Simulator=ease of
engine cranking while
cold
MRV=Mini Rotary
Viscometer=Low
temperature
pumpability
Cold Temp
SAE W viscosity grades for engine oils
Grade
cranking
pumping
0w
3250cP at -30°C
60,000cP at -40°C
5w
3500cP at -25°C
60,000cP at -35°C
10w
3500cP at -20°C
60,000cP at -30°C
15w
3500cP at -15°C
60,000cP at -25°C
20w
4500cP at -10°C
60,000cP at -20°C
25w
6000cP at -5°C
60,000cP at -15°C
Running Temp
SAE viscosity grades for engine oils
Grade
low shear
high shear
20
5.6 - 9.3 cSt at 100°C
2.6 cP at 150°C
30
9.3 - 12.5 cSt at 100°C
2.9 cP at 150°C
40a
12.5 - 16.3 cSt at 100°C
2.9 cP at 150°C
40b
12.5 - 16.3 cSt at 100°C
3.7 cP at 150°C
50
16.3 - 21.9 cSt at 100°C
3.7 cP at 150°C
60
21.9 - 26.1 cSt at 100°C
3.7 cP at 150°C
a (0w-40, 5w-40, 10w-40 grades)
b (15w-40, 20w-40, 25w-40, 40 grades)
How Do Combustion Engines Work?
A General Combustion Engines take
the Linear motion of a piston and
convert it into Rotation. You can
see the piston moving side to
side, connected to the piston is
the rod, which is then connected
to the Crank, which delivers your
rotation to whatever you need it
for. You get the piston to move
by combusting fuel and air
creating a high pressure forcing
the piston down on the “power
stroke”. An engine speed is
rated in RPM (Revolutions per
Minute).
Crank
Rod
Piston
Combustion
Chamber
Why do engines need oil

Lubrication of moving parts
Engines move anywhere from 2000RPM-6000RPM in
Street vehicles and up to 19,000RPM + in Race
Engine. Parts would not last with metal to metal
contact. You need a barrier between parts to cut down
friction, oil is your barrier.

Cooling
Oil also acts as a heatsink for the engine, and as stated
above, you need oil to cut down friction, if there was
no oil the heat caused from friction would be enough
to destroy any engine.
 Cleaning
Oil acts in another way, it removes dust
particles that enter the engine, and some of
the carbon build up in the engine. This is
one of the reasons it is important to change
your oil.
So, what happens to an engine
without oil???




Engine Seizes
Parts wear out very rapidly
Catastrophic failures
Holes in Engine Blocks
Questions?