Engine Lubrication Chapter 12

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

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

Engine Oil More than basic crude Does more than lubricate 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

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

Engine Oil (cont'd.) Oil viscosity Multiple viscosity oils 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

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

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

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

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

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

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

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

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

Changing Engine Oil Benefits of changing the oil Oil change intervals 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

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

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

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