Engine Lubrication: Principles, Oil Types, and Maintenance, Assignments of Industrial Technology

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ENGINE

LUBRICATION

Objectives

■ Describe engine lubrication under different service conditions

■ Select the correct engine oil to use

■ Describe the operation of different types of oil filters

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

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

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.)

■ 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

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

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 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