Engine Lubrication Systems

The ILM states that the primary functions of engine lubricating oil include lubrication, cooling and:

Increasing combustion temperature Cleaning and sealing as well as protecting against corrosion Raising octane rating of fuel Changing coolant boiling point

Viscosity, as applied to engine oil, is defined in the ILM as:

The colour of the oil The oil’s resistance to flow The amount of detergent in the oil The amount of fuel dilution in the oil

Multigrade oils such as 5W–30 are formulated to:

Behave like very thick oil at all temperatures Provide suitable viscosity at both low and high operating temperatures Eliminate the need for oil pumps Be used only in manual transmissions

The 'W' in an oil grade such as 5W–30 indicates:

Winter performance characteristics at low temperature Weight in kilograms Water content of the oil Warranty period

The ILM explains that engine oil additive packages may include:

Only dyes for colour Detergents, dispersants, anti-wear agents, corrosion inhibitors and viscosity index improvers Only friction modifiers Only water-repellent agents

A typical full-flow oil filter:

Filters only a small bypass portion of the oil Filters all oil before it reaches the engine bearings Filters only coolant Filters only crankcase vapours

A bypass oil filter system, described in the ILM, is used to:

Filter fuel in the tank Filter a small amount of oil at a finer level in parallel with the main system Control coolant flow Filter intake air

The oil pump used in most automotive engines is usually a:

Centrifugal pump Gear or rotor (gerotor) type positive displacement pump Diaphragm pump Hand-operated pump

Oil pumps are commonly driven by:

The water pump The crankshaft or distributor/camshaft drive The alternator belt only Vehicle road speed sensors

The ILM notes that oil pressure relief valves are designed to:

Increase oil pressure indefinitely Limit maximum oil pressure by bypassing excess flow Reduce coolant temperature Control fuel pressure

Low oil pressure at hot idle may indicate:

Perfect bearing clearances Excessive bearing clearances, worn pump or very low oil level Correct oil viscosity A plugged air filter only

The ILM describes that oil is delivered under pressure primarily to:

Pistons only Main bearings, rod bearings and often camshaft bearings and valve train components Radiator core Fuel injectors

Oil return passages in the engine are used to:

Carry oil from the crankcase to the radiator Allow oil draining back from the top of the engine to the sump Carry fuel vapours out of the tank Carry coolant to the heater core

Positive Crankcase Ventilation (PCV), as mentioned in the module, is used to:

Increase crankcase pressure Remove blow-by gases from the crankcase and reburn them in the engine Vent exhaust gases directly to atmosphere Pressurize the fuel tank

Oil coolers are installed on some engines to:

Heat the oil for cold starts Remove excess heat from the engine oil under heavy operating conditions Cool only the coolant Improve windshield defrosting

Oil analysis, according to the ILM, is used as a diagnostic tool to:

Measure tire wear Detect contaminants, wear metals and coolant or fuel dilution to assess engine condition Check paint thickness Measure brake pad thickness

API and SAE oil ratings are important because they:

Specify tire pressure Indicate performance level and viscosity grade required by manufacturers Determine coolant colour Set radio presets

The ILM notes that using oil not meeting manufacturer specifications can:

Improve emissions Lead to increased wear, deposits, warranty issues and possible engine damage Always improve fuel economy Have no effect on engine performance

Synthetic engine oils differ from conventional mineral oils mainly because they:

Always have lower viscosity at all temperatures Are formulated from chemically engineered base stocks with improved high- and low-temperature performance Cannot contain additives Are not suitable for modern engines

An oil filter's bypass valve is designed to:

Prevent any oil from bypassing the filter Allow oil to flow around a plugged filter element to prevent oil starvation Control coolant flow Increase oil viscosity

The ILM explains that extended oil change intervals are acceptable only when:

Any oil is used with any filter The oil, filter and operating conditions meet manufacturer and industry specifications The vehicle is never driven Fuel economy is poor

Lubrication in the valve train area is usually supplied by:

Splash only from the crankcase Oil galleries feeding up through the block/head to rocker arms, camshafts or followers Coolant passages Exhaust pressure

Oil foaming in the crankcase can lead to:

Increased effective oil pressure Aerated oil with reduced film strength and pressure fluctuations Improved lubrication Lower operating temperature

The lubrication systems ILM emphasizes correct disposal of used oil because:

Oil is biodegradable in all cases Used oil is a controlled waste that must be recycled or disposed of according to regulations Oil can always be dumped on the ground safely Oil disposal has no legal implications

A clogged oil pickup screen in the sump can cause:

Higher oil pressure at all times Oil starvation and low oil pressure to the engine Improved lubrication to bearings Higher fuel economy

From a parts technician’s perspective, lubrication system parts include:

Only spark plugs Oil pumps, pickup screens, pans, filters, cooler assemblies, gaskets and senders Radiator caps only Exhaust pipes and mufflers

Engine oil also helps to cool engine components by:

Insulating them from heat Carrying heat away from internal parts to the sump and oil cooler if equipped Stopping all heat transfer Absorbing coolant

The ILM points out that frequent short-trip operation can cause:

Less condensation in the crankcase Increased moisture and fuel dilution in the oil, requiring more frequent changes Improved oil life Higher operating temperatures

An oil pressure warning light that flickers at idle usually indicates:

High oil pressure Marginal oil pressure due to low level, thin oil or worn components Normal operation A full oil filter

Oil galleries are usually cast or drilled into the block and head to:

Carry coolant Direct pressurized oil to bearings and valve train parts Hold head bolts Route exhaust gases

High-detergent oils as described in the ILM are used to:

Deposit sludge in cool areas Keep contaminants suspended until they can be removed by the filter Reduce oil flow Increase foaming

The ILM stresses that mixing different viscosity grades of oil:

Always improves protection Can change the overall viscosity and may not meet manufacturer specifications Has no effect on oil characteristics Is required at every service

Oil pressure sending units and switches are used to:

Control radiator fans Provide oil pressure information to gauges or warning lamps Measure coolant temperature Operate door locks

Severe-service schedules mentioned in the ILM include conditions such as:

Highway cruising only in mild weather Frequent short trips, dusty conditions, heavy loads and extreme temperatures Vehicle storage in a heated garage Display vehicles that are never run

Oil leaks at gaskets and seals may indicate:

Correct crankcase ventilation Excess crankcase pressure, hardened seals or gasket failure Low oil level only Proper maintenance

The ILM notes that some engines use oil jets under the pistons to:

Pressurize the cooling system Spray oil on piston undersides to assist cooling and lubrication Lubricate the exhaust system Cool the fuel tank

From the ILM perspective, understanding lubrication systems allows the parts technician to:

Perform wheel alignments Recommend correct oil types, filters and lubrication components for each application Set emission standards Replace body panels

Oil level should be checked with the vehicle on level ground because:

It changes oil viscosity Tilted vehicles can give false high or low readings on the dipstick It improves fuel economy It affects coolant flow