Oil Analysis

Maintenance Management Tool

Questions And Answers



Oil Analysis Program Goals ____________________________________________ 1
How to Use Oil Analysis Effectively 2
Keys to Effective Oil Analysis Results 3
Viscosity 4
Fuel Soot 5
Fuel Dilution 6
Water/Anti-freeze Contamination 7
Oxidation 8
Nitration 9
Solids 10
Total Base Number (TBN) 11
Total Acid Number (TAN) 12
Wear Metals/Elemental Analysis
____Iron (Fe)_________________________________________________ 14
____Copper (Cu) 15
____Aluminum (Al) 16
____Chromium (Cr) 17
____Lead (Pb) 18
____Silicon (Si) 19
____Sodium (Na) 20
____Nickel (Ni) 21
____Silver (Ag) 22
____Molybdenum (Mo) 23
____Magnesium (Mg) 24
____Boron (B) 25
____Calcium (Ca) 26
____Barium (Ba) 27
____Zinc (Zn) 28
____Phosphorus (P) 29




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






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.




Determine Goals and Objectives
Verify Lab Capabilities and Responsiveness
Ensure Samples are Taken Correctly
Take Samples on a Regular Basis
Fill Out Laboratory Sample Information Forms Completely
Do Not Hold Samples. Send to Laboratory ASAP
Tell the Lab of Recent Maintenance or Unusual Problems
Use Manufacturers Guidelines
Involve Your lubricant Supplier
Ensure Good Communications Between Laboratory, Maintenance Personel

and Maintenance Managers

Train Maintenance Personnel About Using Oil Analysis Effectively
Use Oil Analysis as a part of your maintenance Planning and Practices
Evaluate Cause and Effect Relationships in Test Results and Determine

Possible Solutions





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. 100 Centigrade or 40 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:

___Normal ___High ___Low

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


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.





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.


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


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


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.





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.


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.




Many problems cause water/coolant contamination in engine or gear lubricants.


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.


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.


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.




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.


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.


Increased Oil Viscosity Lacquer Build-up
Filter Plugging Metal Parts Corrosion
Over Heating Increased Wear
Engine Performance Problems Sludge Deposits


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.





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.


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


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


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





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.


Air/Fuel Ratios Incorrect Environmental Contaminants
Extended Oil Drains Wear Debris
Fuel Soot Oxidation/Nitration
Blow-by Bad Rings
Over Heating


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.


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.





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


High Acid Levels Additive Depletion
Corrosion Shortened Oil Life
Increased Repair Expense Improper Operations


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





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


Increased Wear Metal Corrosion
Increased Viscosity Increased oxidation
Increased Maintenance Expense Overheating


Reduce Oil Drain Intervals Change Oil
Ensure Correct Oil is Used Replace/Repair Worn Parts
Control Environmental Contaminants Correct Overheating Problems





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.






cylinders, liners, blocks, crankshafts, gears, camshaft, valve train

Differentials - Final Drives - Planetarys - Etc.

gears, shafts, bearings, housing, PTO's


gears, discs, housings, bearing, pumps, brake bands

Hydraulic Systems

pump/motor, vanes, gears, pistons,bearings, rods, housing metal


crankshafts, housing, screws, bearings, oil pumps, piston rings, cylinders,

shafts, blocks




bushings, bearings, cam bushings, oil coolers, valve train bushings,

thrust washers, oil pumps

Differentials - Final Drives - Planetarys - Etc.

bushings, thrust washers, oil pumps


clutch plates, discs, oil coolers, bearing/thrust washers

Hydraulic Systems

pump pistons, cylinder guides, bushings, oil coolers (some)

thrust plates, power steering systems


wear plates, bushings, wrist pin bushings, bearings, thrust washers,

cylinders, shafts, blocks




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


pumps, clutches, thrust washers, bushings

Hydraulic Systems

pump/motor housing, cylinder systems


rotors, pistons, blocks, housing metal, thrust washers





rings, roller/taper bearings (some), liners, exhaust valves, wear treatment

Differentials - Final Drives - Planetarys - Etc.

roller/taper bearings (some)


roller/taper bearings (some), water treatment (oil cooler)

Hydraulic Systems

rods, spools, roller/taper bearings (some)


rings, roller/taper bearings (some), water treatment (oil cooler)





bearings, gasoline, octane improver

Differentials - Final Drives - Planetarys - Etc.

oil additives (some)


oil additives (some)







anti-foam additives, ingested dirt

Differentials - Final Drives - Planetarys - Etc.

ingested dirt


disc lining


ingested dirt





oil additives (some), anti-freeze, road salt, ingested dirt

Differentials - Final Drives - Planetarys - Etc.

ingested dirt


oil additives, anti-freeze, road salt, ingested dirt

Hydraulic Systems

oil additives, anti-freeze, ingested dirt


oil additives, ingested dirt, anti-freeze



certain types of bearings, valve and valve guides



certain types of bearings, solder in some oil coolers



plating or surface hardening agent in certain bearings, rings



case and/or body wear of certain engines, cases of certain accessory gear boxes,

oil additives (usually as detergent-dispersants)


In addition to wear metals, there are other metallic additives present to a certain degree in most modern lubricants. They include:


anti-wear agents, antioxidants, constituent of deodorant cutting oils,

grease, brake fluids



detergents, dispersants, acid neutralizers



corrosion inhibitors, detergents, rust inhibitors



anti-oxidants, corrosion inhibitors, anti-wear additives,

detergents, extreme pressure additives



anti-rust agents, spark plug and combustion chamber deposit reducers