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

Engine Oil • More than basic crude – Contains a complicated additive package • First additives were developed in the 1930 s • 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

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 20 W-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

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

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

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

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 © 2012 Delmar, Cengage Learning