Lubrication System

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Chapter 41
Lubrication System Fundamentals
2
Function of Oil

• Lubricates
• Reduces friction between moving parts
• Cleans
• Carries contaminates to filter
• Cools
• Helps to dissipate heat
• Seals
• Prevents leakage past rings and seals

3
Organizations

• API (American Petroleum Institute)
• S rating for Spark Ignition Engines
• SA1974
• SLCurrent
• C rating for Compression Engines
• CA1974
• CHCurrent
• SAE (Society of Automotive Engineers)
• Are responsible for the testing and
  classification of oils

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Viscosity

• A fluids resistance to flow
• Thicker oils have a higher viscosity
• Water has almost no viscosity
• It is the property of an oil to develop and
  maintain a certain amount of shearing stress
  dependent on flow

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Weight Rating

• 10W-30
• Oil acts like a 10 weight oil at 0 degrees
  Fahrenheit
• Oil acts like a 30 weight oil at 212 degrees
  Fahrenheit
• Thicker oils have better protection but there is
  a trade off.
• What is that trade off?
• To thick the engine requires more energy to turn
  crankshaft

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Single and Multiviscosity Oils

• Single viscositySAE 20, 30 or 40
• limited range of operating temperatures
• not as stable as multiviscosity oil
• MultiviscositySAE 10W-30, 20W-50
• exhibits characteristics of a thin light oil when
  cold and a thicker, heavy oil when hot

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Oil Viscosity Rating

• Determined by measuring how long oil takes to
  flow through a specific opening at a specific
  temperature

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Viscosity Index

• Is a number indicating the rate of change in
  viscosity of an oil within a given temperature
  range
• A high number indicates a low change
• The higher the number the better

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Flash Point

• The temperature at which an oil gives off vapors
  that can be ignited with a flame
• If vaporization occurs it can cause oil to burn
  off the cylinder walls
• The higher the flash point the better

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Pour Point

• Pour point is 5 degrees Fahrenheit about the
  point at which oil shows no movement for 5
  seconds
• Borderline pumping temperature is about 20
  degrees above the pour point
• This is a temp that the oil pump can maintain
  adequate oil pressure

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Sulfated Ash

• Amount of solid material left when the oil burns
• High ash content will tend to form more sludge
  and deposits in the engine
• Low ash content also seems to promote long valve
  life

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Additives

• Viscosity improvers
• Antioxidants
• Detergents
• Foam inhibitors

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Antioxidants

• As oil is used it combines with oxygen and picks
  up contaminants
• Rust
• Combustion byproducts
• Condensed water
• Acids
• Results in the formation of sludge and varnish
• Frequent oil changes are still the best way to
  combat this problem

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Detergents

• Prevent the build-up of deposits in an engine
• They keep unwanted products like metal deposits
  suspended in the oil so that they can be caught
  by the filter
• They are the reason why your oil gets dirty

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Oil Sludge
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Foam Inhibitors

• Whipping through the oil causes foaming
• Foamy oil is not as effective as a lubricant
• Oxidation is accelerated
• Inhibitors cause foam bubbles to collapse

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Synthetic Oil

• Man made
• Vegetable oils
• Can be made from crude
• Refined so much that it is no longer a crude oil
• Advantages
• Better viscosity at cold temperatures
• Better protection at high temperatures
• Disadvantages
• Very expensive

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Typical Lubrication System
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Oil Film

• Oil film separates engine parts, preventing
  metal-on-metal contact

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Oil (Bearing) Clearance

• Small space between moving parts, about .002
  (0.05 mm)

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Bearing Types
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Shaft-Driven Oil Pump
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Rotary Oil Pump

• Inner rotor is driven by the pump shaft and turns
  the outer rotor

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Spin-On Oil Filter
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Filter Oil Flow
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Oil Cooler

• Heat exchanger to lower and control temperature
  of the engine oil

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Oil Spray Nozzles

• Direct a stream of oil onto the bottoms of the
  pistons, timing gears or chain

Fig 27
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Positive Crankcase Ventilation System

• Draws fumes out of the engine crankcase
• Burns fumes in the engine
• Prevents engine sludging

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Checking Fluids

• Engine Oil
• Engine not running

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Checking Fluids

• Auto Trans Fluid
• In park
• Engine Running

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Checking Fluids

• Power Steering
• Engine not running

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Checking Fluids

• Manual Trans
• Check under vehicle at fill plug
• Fluid should be level with plug

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Checking Fluids

• Differential
• Check under vehicle at fill plug
• Fluid should be level with plug

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Checking Fluids

• Transfer Case
• Check under vehicle at fill plug
• Fluid should be level with plug

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Maintenance

• Engine Oil Change
• Every 3,000 to 5,000 miles with crude oil and
  hazardous driving conditions
• Transmission oil change
• Every 50,000 miles depending on use
• Power Steering Fluid
• Every 50,000 miles
• Manual Gear Case
• Every 50,000 miles

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Grease Job
Grease all fittings at each oil change