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© 2012 Delmar, Cengage Learning
Engine Lubrication
Chapter 12
© 2012 Delmar, Cengage Learning
Objectives• Describe engine lubrication under different
service conditions• Select the correct engine oil to use• Describe the operation of different types of oil
filters
© 2012 Delmar, Cengage Learning
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
© 2012 Delmar, Cengage Learning
© 2012 Delmar, Cengage Learning
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
© 2012 Delmar, Cengage Learning
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
© 2012 Delmar, Cengage Learning
© 2012 Delmar, Cengage Learning
© 2012 Delmar, Cengage Learning
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
© 2012 Delmar, Cengage Learning
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
© 2012 Delmar, Cengage Learning
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
© 2012 Delmar, Cengage Learning
© 2012 Delmar, Cengage Learning
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
© 2012 Delmar, Cengage Learning
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
© 2012 Delmar, Cengage Learning
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
© 2012 Delmar, Cengage Learning
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
© 2012 Delmar, Cengage Learning
© 2012 Delmar, Cengage Learning
Oil Additives (cont'd.)• Nondetergent oil
– Oil without additives is called
• Oil oxidizes at temperatures higher than 250°F– Becomes thicker and forms varnish deposits
– Oxidation rate doubles every 20°F above 140°F
– Antioxidants combat the effects of heat on the oil
– Detergents make varnish oil soluble
© 2012 Delmar, Cengage Learning
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
© 2012 Delmar, Cengage Learning
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
© 2012 Delmar, Cengage Learning
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
© 2012 Delmar, Cengage Learning
© 2012 Delmar, Cengage Learning
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
© 2012 Delmar, Cengage Learning
© 2012 Delmar, Cengage Learning
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
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