Engine Lubrication

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Engine Lubrication

• Chapter 12

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Objectives

• Describe engine lubrication under different
  service conditions
• Select the correct engine oil to use
• Describe the operation of different types of oil
  filters

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Introduction

• All moving parts are separated by a thin oil
  layer
• Oil pump supplies oil to the engine
• Little wear should occur if oil is maintained
  properly

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Engine Oil

• More than basic crude
• Contains a complicated additive package
• First additives were developed in the 1930s
• Does more than lubricate
• Cools, cleans, and prevents rust
• Fills hydraulic valve lifters or cam followers
• Helps seal piston rings against cylinders

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Engine Oil (cont'd.)

• Oil level
• Correct level is designed to keep the oil pickup
  screen below the level of the oil
• When checking oil level
• Vehicle should be on a level surface
• Engine should be warm but off for five minutes
• Push dipstick all the way down
• If level is unclear look at back of dipstick or
  re-dip
• If level is low check if the vehicle is due for
  service

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Engine Oil (cont'd.)

• Oil viscosity
• Oil thickness or body
• Multiple viscosity oils
• Most new engine oils are multiple viscosity
• Viscosity index
• Ability to resist change in viscosity under
  increased heat

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Engine Oil (cont'd.)

• Oil pressure
• Develops when there is a resistance to flow
• As engine wears, clearance between crankshaft and
  bearings increases
• Oil pump cannot fill extra clearance
• Oil pressure is low when engine idles
• SAE 20W-50 provides higher oil pressure in older,
  idling engines
• Flows more slowly to bearings of new engine when
  first started on a cold morning

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Engine Oil Licensing and Certification

• SAE decides when new oil specifications are
  needed
• American Society for Testing and Materials
• Sets performance specifications
• American Petroleum Institute
• Administers the licensing and certification
• Starburst symbol
• API licenses engine oil marketers to display its
  starburst certification mark

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Engine Oil Licensing and Certification (cont'd.)

• Oil service ratings
• Set by API
• SA through SN
• SA mineral oil with no additives and is not
  recommended for automotive use
• S used for engines with a spark
• Diesel engine oils rated CA through CJ

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Engine Oil Licensing and Certification (cont'd.)

• European ACEA oils
• ACEA standards developed by European auto
  manufacturers
• Manufacturer-specific oil standards
• Becoming more common
• Energy-efficient oils
• Oil is energy conserving if it passes certain
  tests
• Energy conservation ratings began in 1994
• HTHS viscosity rating
• Measures viscosity under difficult conditions

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Oil Additives

• Additives make up as much as one-third of the
  volume of the oil
• Additives found in engine oil
• Pour-point depressants
• Corrosion and rust inhibitors
• Antifoam additives
• Friction modifiers
• Oxidation inhibitors
• Antiwear additives

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Oil Additives (cont'd.)

• Boundary lubrication
• Film becomes too thin or breaks down under load
• Detergents and dispersants
• Keep small particles suspended
• As oil decomposes at high temperatures it reacts
  with oxygen to form a gummy mixture
• Detergents make deposits oil soluble
• Sludge
• Mixture of moisture, oil, and contaminants
• Clogs oil screen and oil lines if it accumulates

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Oil Additives (cont'd.)

• Nondetergent oil
• Oil without additives is called
• Oil oxidizes at temperatures higher than 250F
• Becomes thicker and forms varnish deposits
• Oxidation rate doubles every 20F above 140F
• Antioxidants combat the effects of heat on the
  oil
• Detergents make varnish oil soluble

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Synthetic Oils

• Molecules are nearly the same size
• Reduces friction
• Contain no wax or impurities
• Suited to lower temperatures
• Can also withstand higher temperatures
• Advantages
• Lower oil consumption
• Can be changed less frequently
• Disadvantage
• Price

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Changing Engine Oil

• Benefits of changing the oil
• Oil additives are depleted over time
• Cleans smaller contaminants from the oil
• Unburned contaminants are removed with the oil
• Sludge is removed
• Oil change intervals
• Vehicles driven primarily on the highway can
  change oil every 7,500 miles
• Newer engines with VTT require regular oil
  changes with high-quality, low-viscosity oil

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Changing Engine oil (cont'd.)

• Changing brands of oil
• Avoid mixing brands between oil changes
• Best done when the oil is being changed
• Use any brand of high-grade oil when there is no
  choice of brand available
• Changing oil
• Best to change oil when it is still hot
• Mileage service record usually a sticker
• Oil monitor system reset
• Included in many late-model vehicles

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Oil Filter

• Prevents harmful abrasive particles in the oil
  from damaging internal parts
• Today's cars use the full-flow oil filter
• Must have a by-pass valve
• Horizontal mounted filters
• Have an anti-drainback valve
• By-pass oil filters
• Supplemental add-on filters used on heavy trucks
• Variations in filters
• Identified by a number printed on the metal shell

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Changing the Oil Filter

• Considerations
• Sheet metal shell on filter is very thin
• Rubber O-ring seals filter against engine block
• Make sure there is not an old seal stuck to the
  engine block
• Lubricate the O-ring with oil prior to
  installation
• Most filters have instructions printed on the
  outside
• Overtightening will make future removal difficult