Oil Analysis
Maintenance Management Tool
Questions And Answers
TABLE OF CONTENTS:
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OIL ANALYSIS PROGRAM
GOALS
 Reduce Unscheduled Downtime |
| Extend Equipment Life |
| Extend Oil Change Intervals |
| Evaluate Lubricant Condition |
| Reduce Maintenance Expense |
| Measure Fleet Wear Trends |
| Determine Proper Maintenance Intervals |
| Verify Abnormal Condition |
| Increase Maintenance Production |
| Reduce Repair Parts Inventories |
| Reduce Equipment Replacement Costs |
| Identify Corrections/Repairs Needed in Equipment |
| Support Warranty Claims |
| Enhance Scheduling of Repairs |
| Identify Maintenance Discrepancies and Operator Abuse |
| Increase Equipment Reliability |
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HOW TO USE OIL
ANALYSIS EFFECTIVELY
Used oil analysis is very effective when used as a part of your
maintenance management program. However, never rely on oil analysis test results alone
when making maintenance decisions!
Obtain information from all sources before making your final
maintenance decision. Typical sources of information to consider are:
| Driver Logs/Information |
Equipment Manufacturer |
| In Shop Diagnostic Test Information |
Lubricant Suppliers |
| Operating Conditions/Environment |
Equipment Maintenance History |
| Visual Inspection |
Compare Current Sample Results With Previous Samples |
| Evaluate Fuel Source Quality |
Age of Equipment |
| Evaluate Impact of Recent Maintenance Repairs |
Compare Individual Units to Fleet Trend |
Oil analysis is a reliable and effective maintenance management
tool and the information provided by the laboratory can assist you in making more informed
maintenance decisions. The laboratory, lubricant supplier and equipment manufacturer are
an important part of your team and should be involved in your program.
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KEYS TO EFFECTIVE OIL
ANALYSIS RESULTS
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VISCOSITY
Viscosity is the single most important
property of lubricating oils. A viscosity test measures the lubricants internal resistance
to flow. Put simply, how thick or thin the lubricant is. Test results are reported in
Centistokes (cSt). SAE viscosity or Saybolt Universal Seconds (SUS).
Viscosity test are typically run at one of
two temperatures i.e. 100º Centigrade or 40º Centigrade. The laboratory and your
lubricant supplier can advise you in determining the best temperature range to select.
Viscosity test results are typically
recorded three ways:
High or low results should be investigated to
determine the cause and maintenance should be initiated to correct the problem.
Changes in the viscosity indicate the degree of
aging, by-product contamination, dilution, the possibility of mixed products, and other
abnormalities that affect the serviceability of the lubricant.
CAUSES of Viscosity Problems:
| Fuel Dilution |
Oxidation
Varnish/Sludge |
| High Levels
of Soot |
Overextended
Oil Drains |
| Water
Contamination |
Mixed
Lubricants |
| Anti-freeze
Contamination |
Additive
Shearing/Breakdown |
| Blow-by |
Incorrect
Lubricant Use |
MAINTENANCE ACTIONS:
| Check Operating Temperature |
Check Air
to Fuel Ratio |
| Check for
Contaminated New Oil |
Check for
High Soot Loading |
| Check Oil
Grade |
Check for
Fuel Dilution |
| Evaluate
Equipment Operations |
Evaluate
Oil Drain Intervals |
| Check for
Excessive Idling or Lugging Conditions |
Check for
Water Contamination |
| Repair/Replace
Defective Seals |
Change Oil
and Filters |
| Test for
Solids in the Lubricant |
Check for
Leaking Injectors |
| Check for
Anti-freeze Contamination |
Ensure
Equipment is Operated Properly |
| Check for
Varnish and Sludge Formation |
Ensure
Correct Lubricants are in use |
Abnormal changes in viscosity are serious and
require immediate maintenance action. Viscosity problems can shorten equipment life, cause
breakdowns, increase maintenance costs and affect productivity.
Many variables must be taken into consideration when
evaluating viscosity problems. Some of these variables are:
| Age of Equipment |
Operating
Conditions |
| Environmental
Factors |
Equipment
Applications |
| Cost of
Repair vs. Replacement |
Type of
Equipment |
| Operator/Driver
Training |
Maintenance
Scheduling |
| Warranty
Claim Potential |
Cause of
the Abnormal Viscosity |
| Effect of
Wear Metals |
Miles or
Hours on Equipment |
| Miles or
Hours on Lubricant |
Company
Maintenance Goals |
As a standard, increase or decrease in viscosity by
one grade, depending on variables involved, should be evaluated for maintenance for
maintenance action or inspection. Always check with the lubricant supplier and the
equipment manufacturer to determine the properly specified viscosity and type of lubricant
you should use. Properly specified oil, kept clean and free of contaminants will provide
good serviceability and help to ensure long equipment operation and life at a reduced
cost.
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FUEL SOOT
Measuring the amount of fuel soot in diesel
engine oils is an excellent method used to determine the combustion efficiency of an
engine. The fuel soot test will help you determine if air to fuel ratios are incorrect or
if other abnormalities exist. Excessive levels of fuel soot can cause many problems and
maintenance action should be taken as soon as possible to make corrections. Fuel soot,
also, may cause excessive exhaust emissions resulting in violation of state and city
emissions standards.
CAUSES
| Improper Air to Fuel Ratio |
Injector Adjustment Incorrect |
| Improper Equipment Operation |
Clogged Air Filters |
| Poor Fuel Quality |
Defective Injectors |
| Worn, Stuck Compression Rings |
Stuck Oil Rings |
| Intake/Exhaust Valve Guide Problems |
Out of Round Cylinders |
| Low Compression |
Overextended Oil Drains |
| Excessive Idling |
Defective Oil Cooler |
EFFECTS
| Increased Viscosity |
Restricted
Oil Flow |
| High Engine
Temperature |
Clogged
Filters |
| Oxidation |
Lacquer
Build-up |
| Loss of
Power/Performance |
Excessive
Emissions |
| Shortened
Oil Drains |
Engine Life
May Be Shortened |
| Increased
Maintenance Cost |
Loss of
Productivity |
MAINTENANCE ACTIONS
| Ensure Air to Fuel Ratios are Correct |
Ensure Air
Filters are Changed |
| Evaluate
Fuel Quality |
Change Oil
Filters |
| Train
Drivers/Operators |
Check
Compression |
| Shorten Oil
Drain Intervals |
Replace
Rings |
| Avoid
Excessive Idling |
Check/Correct
Timing |
| Ensure
Piston Crowns are Clean and Free of Carbon Build-up |
Ensure
Operating Temperatures are correct |
| Check
Injector Spray Patterns |
Check Fuel
Metering |
| Replace/Repair
Injectors |
Check/Adjust
Governor |
| Check/Adjust
Exhaust Valve Clearance |
Check
Supercharger Operation |
Fuel soot problems can be the result of many things, however, if
the tune-up procedure of the manufacturer are followed and proper lubricants are used,
these should be corrected.
The effects of high soot loading are varied and depend on the
composition of the soot.
The amount of fuel soot detected is reported as % weight. Typical
warning levels start around 1.5%. However, depending on the engine type, the application,
and the way the fuel soot is developed, its effects on the lubricant, engines and filters
can be significantly different. Soot from improper air to fuel ratios may have a different
effect than soot caused by compression problems.
Fuel soot levels combined with viscosity results provide an
excellent indication of the lubricant condition and the efficiency of the engine.
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FUEL DILUTION
When excessive fuel dilution occurs, the
effectiveness of the lubricant is reduced. As the fuel thins the lubricant, the viscosity
goes down and may allow increased wear which in turn may cause overheating. Oil needs to
keep the metal parts separated, to provide sealing from combustion products and transfer
heat from the engine for cooling. When the oil is diluted by the fuel, its ability to
perform is diminished and the effects can lead to engine failure.
CAUSES
| Leaking/Defective
Injectors |
Driving
Conditions |
| Excessive
Idling |
Leaking
Fuel Pump/Lines |
| Incomplete
Combustion |
Equipment
Application |
| Worn
Liners/Rings |
Incorrect
Air to Fuel Ratio |
| Improper
Timing |
Poor Fuel
Quality |
| Inexperienced
Drivers/Operators |
Equipment
Use vs. Design |
To avoid fuel dilution problems it is necessary to ensure the
causes are corrected. Refer to the fuel section for more solutions
If possible, another sample should be sent to the laboratory to
verify results. Samples may be contaminated during the oil drain and sampling. Always
ensure clean, uncontaminated sampling materials are used. Do not drop the oil into a fuel
contaminated container when sampling. If using sample pumps, do not reuse the sample
tubing.
Fuel dilution problems require immediate attention! Fuel dilution
can effect all other test results and may interfere with proper maintenance evaluation of
equipment and lubrication condition. Depending on the variables involved, fuel dilution of
2.5% to 5.0% is considered excessive and requires maintenance action and/or repair.
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WATER/ANTIFREEZE
CONTAMINATION
Many problems cause water/coolant
contamination in engine or gear lubricants.
CAUSES
| Low
Operating Temperatures |
Defective
Seals |
| Blown Head
Gasket |
New Oil
Contamination |
| Head bolt
Torque Incorrect |
Improper
Storage of New Oil |
| Holes in
Liners |
Combustion
Products |
| Contamination
from Maintenance |
Oil Cooler
Leaks |
| Head and
Block Surfaces Improperly Machined |
Sample
Contaminated During Sampling |
Used oil analysis will seldom detect water in engine
oils because engine oils are hot enough to evaporate the water. However, the chemical
components of anti-freeze remain in the oil and are detected as parts per million (ppm) of
Sodium (Na), Boron (B), and Potassium (K). When elevated amounts of Na, B, or K are
detected in crankcase oils, it usually means anti-freeze contamination has occurred. Some
lubricants contain these elements and used oil results must be compared to new results to
determine if contamination is present.
The effects of water and/or anti-freeze
contamination are well known to mechanics and equipment operators.
EFFECTS
| Engine/Equipment
Failure |
Acid
Formation |
| Ineffective
Lubrication |
Weld Spots |
| High
Operating Temperatures |
High Levels
of Wear Metals |
| Power Loss |
Increased
Viscosity |
| Metal
Corrosion |
Coolant
Loss |
| Lubricant
Additive Properties become ineffective |
Milky
Appearance of Lubricant |
Solutions to Water/anti-freeze contamination are
many and varied and depend on the engine involved.
MAINTENANCE ACTIONS
| Check
Torque on Head bolts |
Inspect Oil
Coolers |
| Check or
Change Gaskets |
Check New
Oil for Contamination |
| Check
Internal and External Seals |
Evaluate
Operating Conditions |
| Inspect
Heads and Block for Damage |
Avoid
Intermittent Use |
| Always
Change Oil and Filters When Contamination is Suspected |
Ensure
Correct Lubricant is in Use |
Laboratory analysis is an effective method for
identifying water or anti-freeze contamination before problems occur. Infrared analysis is
used to determine the amount of water by % volume in used oil. For equipment application
with greater sensitivity to moisture, the Karl Fischer apparatus will measure amounts in
parts per million.
These contaminants are serious and their causes
should be investigated and corrected. However, always consider the cause of the problem
when determining the need for repairs or maintenance. Verify lab results by inspection,
resample and other tests, if possible.
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OXIDATION
Engine Oil and oil in various other
components can, under certain conditions, undergo a chemical change resulting in
oxidation. This process can cause harmful by-products and affects the oils ability to
lubricate.
Common problems resulting from high
oxidation and by-products are:
| Lacquer
Deposits |
Metal
Corrosion |
High
Viscosity |
the oil analysis lab can compare a sample of used oil to a sample
of new oil and determine the extent of oxidation problems. Oxidation breakdown is
considered to be one of the most important problems affecting the serviceability of a
lubricant.
CAUSES
| High
Operating Temperatures |
Wrong Oil
in Service |
| Combustion
By-products/Blow-by |
Extended
Oil Changes |
Overextended oil drains are probably the most common cause of
increased oxidation.
EFFECTS
| Increased
Oil Viscosity |
Lacquer
Build-up |
| Filter
Plugging |
Metal Parts
Corrosion |
| Over
Heating |
Increased
Wear |
| Engine
Performance Problems |
Sludge
Deposits |
MAINTENANCE ACTIONS
| Shorten Oil
Drains |
Control
High Temperatures |
| Use Correct
Lubricants |
Change Oil
and Filters |
| Ensure
Equipment is used Properly and Under Proper Operating Conditions |
| Ensure
Oxidation Results and Accurate. Changes in the Blend of a Product May Affect the Lab
Results. Typically, Oxidation Tests are not Performed on Synthetic Lubricants. |
| Ensure
Products are not Mixed by Brand Types. Mixtures May Indicate Oxidation Problems When None
Exist. |
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NITRATION
The products of Nitration are highly acidic, cause
deposits can increase the effects of oxidation.
These products are performed during the fuel
combustion process when combustion by-products mix with the engine oil. This occurs during
normal operation or as a result of abnormal blow-by.
The standard method of measuring the amount of
nitration occurring is by Infrared analysis. Increase in the Total Acid Number (TAN), a
measure of the acid in the oil, can also occur when high levels of nitration are present.
When high nitration levels are present, the
serviceability of the lubricant is affected.
Nitrogen compounds are often found in the fuel,
especially fuel having a high sulfur content.
CAUSES
| Turbo/Super
charger Problems |
Scavenge
Pump Problems |
| Compression
Problems |
Fuel
Problems |
| Improper
Scavenge |
Low
Temperature Operations |
| Abnormal
Blow-by |
Air/Fuel
Ratio Incorrect |
| Defective
Seals |
Bad Rings |
EFFECTS
| Acid
Increase |
Wear Metal
Corrosion |
| Accelerated
Oxidation |
Increase
Wear |
| Ring
Sticking |
Oil
Viscosity Increase |
| Carbon
Deposits |
Lower
Productivity |
| Increased
Maintenance Expense |
Environmental
Contamination from Nitrous Oxides |
MAINTENANCE ACTIONS
| Correct
Operating Temperatures |
Perform
Compression Checks |
| Correct
Scavenge Problem |
Check
Crankcase Venting |
| Check Fuel |
Correct
Air/Fuel Ratio |
| Change Oil
Filters |
Correct
Other Problems |
| Ensure
Correct Oil is Used |
Replace
Compression Rings |
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TOTAL SOLIDS
Total solid contamination usually indicates
in system contamination or lubricant degradation. The type detected depends on the system.
Typically, solid components come from sources such as fuel soot, wear debris and oxidation
products.
High levels of solids indicate other
problems are affecting the lubricant and the reason for the solids should be investigated
and corrective action should be accomplished.
CAUSES
| Air/Fuel
Ratios Incorrect |
Environmental
Contaminants |
| Extended
Oil Drains |
Wear Debris |
| Fuel Soot |
Oxidation/Nitration |
| Blow-by |
Bad Rings |
| Over
Heating |
|
EFFECTS
| Power Loss |
Viscosity
Increase |
| Sludge
Build-up |
Lacquer
Formation |
| Increased
Wear |
Plugged
Filters |
| Higher
Operating temperature |
Poor
Lubrication |
| Solids
will affect the lubricant and equipment in many ways. Solids interfere with the flow of
the oil and can keep many parts from receiving proper lubrication. |
MAINTENANCE ACTIONS
Correct and/or repair all components that contribute to the
causes. Control the cause and most of the effects will be eliminated.
| Use
Equipment Correctly |
Control
Operating Conditions |
| Always
Change Oil |
Always
Change Filters |
| Check
with the oil supplier and lubricant manufacturer to ensure correct lubricants are in use
and to obtain information regarding preventative maintenance action. |
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TOTAL BASE NUMBER
(TBN)
Depending on the application and use, an oil will
have additives added to protect the lubricant properties and the equipment.
Base (alkaline) additives are in the oil to
neutralize acidic products. The additives have a limit to their ability neutralize acids.
Over use of a lubricant, i.e. extended oil drains, will cause the base additives to lose
their ability to neutralize acids.
New oils start with the highest TBN they will
possess. Depending on the equipment, application and operation lubricants are developed
with different amounts of these additives.
Measuring the TBN is very important when extending
oil drain intervals. The levels of the TBN will indicate the capability of the additives
to neutralize the acids.
When the TBN is reduced to 1/2 of its original value
an oil change is advisable.
Calcium (Ca) and Magnesium (Mg) are the additives
blended with oil to neutralize acids and acid by-products. Calcium and Magnesium levels
indicate the amount of these additives in new oil. These levels will remain in the oil
even though they can no longer neutralize acids. TBN testing is the only way to determine
if these additives remain effective.
CAUSES (of low TBN readings)
| Incorrect
Oil in Use |
Acid Build
Up |
| Fuel Sulfur |
Nitration |
| Overextended
ODI's |
Over
Heating |
| Blow-by |
Improper
Operations |
EFFECTS
| High Acid
Levels |
Additive
Depletion |
| Corrosion |
Shortened
Oil Life |
| Increased
Repair Expense |
Improper
Operations |
MAINTENANCE ACTIONS
| Ensure Low
Sulfur Fuel is Used |
Use Correct
Lubricants |
| Verify TBN
of New Product |
Change Oil |
| Add Fresh
Oil, if Possible |
Test Fuel
Quality |
| Repair/Replace
Worn or Defective Engine Parts |
Shorten Oil
Change Interval |
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TOTAL ACID NUMBER
(TAN)
The TAN test measures the amount of acid or
acid-like contaminants in the oil. Increase in the TAN above the level in new lubricants
should be monitored.
TAN increases normally indicate lube
oxidation or contamination with acidic products has occurred.
New oils normally have a low level of
acids. This is because some additives used in the development of new oils are acidic in
nature.
Acids and/or acidic by-products affect the
serviceability of lubricants and may cause other related problems. Corrective action is
required.
CAUSES (high TAN results)
| Poor Fuel
Quality |
High Sulfur
Fuel |
| Over
Extended Oil Change |
Wrong Oil
use |
| Additive
Depletion |
Excessive
Blow-by |
| High
Temperature Operation |
Environmental
Sources |
| Worn/Defective
Engine Parts |
|
EFFECTS
| Increased
Wear |
Metal
Corrosion |
| Increased
Viscosity |
Increased
oxidation |
| Increased
Maintenance Expense |
Overheating |
MAINTENANCE ACTIONS
| Reduce Oil
Drain Intervals |
Change Oil |
| Ensure
Correct Oil is Used |
Replace/Repair
Worn Parts |
| Control
Environmental Contaminants |
Correct
Overheating Problems |
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WEAR
METALS/ELEMENTAL ANALYSIS
Equipment as it operates will deposit microscopic amounts of wear
metals in the lubricant. Under normal conditions, wear will be very gradual and will
increase slowly as the equipment is used. Samples taken regularly, allow the development
of a baseline for each piece of equipment and subsequent samples are checked against the
baseline for unusual increases or changes. Unusual increases or changes from established
trends should be evaluated to determine the cause and possible effect.
Included in the oil analysis element testing are elements
representing additives and contaminants. The additive elements can help to ensure the
correct lubricant is in use and the contamination elements help to pinpoint specific
problems.
The cause and effect relationship of the various wear elements to
each other, to the additive elements, to the contamination elements and to changes in
lubricant properties must carefully be considered when making maintenance decisions.
A short list of cause and effect relationships is as follows:
| Dirt
(Silicon) ingestion may cause increase wear metals. |
| Copper,
Tin, and Lead wear may indicate bearing wear. |
| Iron,
Aluminum, and Chromium wear may indicate cylinder wear. |
| Low or high
additive elements may indicate the incorrect oil is in use. |
| Contamination
elements, Sodium, Potassium, and/or Boron, may indicate coolant leaks and explain changes
in viscosity. |
| High wear
metals (elements) with a low (abnormal) viscosity may indicate a fuel dilution problem. |
| High wear
metals (elements) may occur because of abnormally high viscosity, high soot loading and
water or anti-freeze contamination. |
| High or low
additives may indicate contamination or the incorrect lubricants in use. |
| Additives
are useful in determining the capability of lubricant to neutralize acid. |
| Silicon
without wear metals may indicate a contaminated or improperly taken sample or may be from
a lubricant using silicon as an anti-foam agent. |
| High levels
of cylinder wear may allow increases in the amounts of blow-by or soot. |
| Increased
levels of soft metals i.e. Copper, Lead. and Tin may result from poor lubrication because
of water and/or anti-freeze contamination. |
| High acid
levels may cause corrosion of wear metals. |
| Over
extended oil drains, overheating, improper operation and many other factors can affect the
wear metals present in the lubricant. |
It is very difficult to pinpoint the source of wear metals,
however, by determining abnormal problems causing the wear and correcting these problems,
many times the wear can be controlled or prevented.
Wear metal elements, additive elements and contamination elements
come from many different sources. Typical sources are as follows.
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IRON (Fe)
Engines
cylinders, liners, blocks, crankshafts, gears,
camshaft, valve train
Differentials - Final Drives -
Planetarys - Etc.
gears, shafts, bearings, housing, PTO's
Transmissions
gears, discs, housings, bearing, pumps, brake
bands
Hydraulic Systems
pump/motor, vanes, gears, pistons,bearings, rods,
housing metal
Compressors
crankshafts, housing, screws, bearings, oil pumps,
piston rings, cylinders,
shafts, blocks
14
COPPER (Cu)
Engines
bushings, bearings, cam bushings, oil
coolers, valve train bushings,
thrust washers, oil pumps
Differentials - Final Drives -
Planetarys - Etc.
bushings, thrust washers, oil pumps
Transmissions
clutch plates, discs, oil coolers,
bearing/thrust washers
Hydraulic Systems
pump pistons, cylinder guides, bushings,
oil coolers (some)
thrust plates, power steering systems
Compressors
wear plates, bushings, wrist pin
bushings, bearings, thrust washers,
cylinders, shafts, blocks
15
ALUMINUM (Al)
Engines
pistons, bearings, blocks (some), bushings,
housing, oil pumps, blowers,
thrust bearings, cam bearings/bushings
Differentials - Final Drives -
Planetarys - Etc.
pump bushings, thrust washers, oil pumps
Transmissions
pumps, clutches, thrust washers, bushings
Hydraulic Systems
pump/motor housing, cylinder systems
Compressors
rotors, pistons, blocks, housing metal, thrust
washers
16
CHROMIUM (Cr)
Engines
rings, roller/taper bearings (some), liners,
exhaust valves, wear treatment
Differentials - Final Drives -
Planetarys - Etc.
roller/taper bearings (some)
Transmissions
roller/taper bearings (some), water treatment (oil
cooler)
Hydraulic Systems
rods, spools, roller/taper bearings (some)
Compressors
rings, roller/taper bearings (some), water
treatment (oil cooler)
17
LEAD (Pb)
Engines
bearings, gasoline, octane improver
Differentials - Final Drives -
Planetarys - Etc.
oil additives (some)
Transmissions
oil additives (some)
Compressors
bearings
18
SILICON (Si)
Engines
anti-foam additives, ingested dirt
Differentials - Final Drives -
Planetarys - Etc.
ingested dirt
Transmissions
disc lining
Compressors
ingested dirt
19
SODIUM (Na)
Engines
oil additives (some), anti-freeze, road salt,
ingested dirt
Differentials - Final Drives -
Planetarys - Etc.
ingested dirt
Transmissions
oil additives, anti-freeze, road salt, ingested
dirt
Hydraulic Systems
oil additives, anti-freeze, ingested dirt
Compressors
oil additives, ingested dirt, anti-freeze
20
NICKEL (Ni)
certain types of bearings, valve and valve guides
21
SILVER (Ag)
certain types of bearings, solder in some oil
coolers
22
MOLYBDENUM (Mo)
plating or surface hardening agent in certain
bearings, rings
23
MAGNESIUM (Mg)
case and/or body wear of certain engines, cases of
certain accessory gear boxes,
oil additives (usually as detergent-dispersants)
24
In addition to wear metals, there are other metallic
additives present to a certain degree in most modern lubricants. They include:
BORON (B)
anti-wear agents, antioxidants, constituent of
deodorant cutting oils,
grease, brake fluids
25
CALCIUM (Ca)
detergents, dispersants, acid neutralizers
26
BARIUM (Ba)
corrosion inhibitors, detergents, rust inhibitors
27
ZINC (ZN)
anti-oxidants, corrosion inhibitors, anti-wear
additives,
detergents, extreme pressure additives
28
PHOSPHORUS (P)
anti-rust agents, spark plug and combustion
chamber deposit reducers
29