Oil is a vital component of your truck’s engine as it affects reliability, fuel consumption, efficiency, and your bottom line. Owner-operators can optimize engine performance and overall truck drivability by identifying performance problems in progress. Oil analysis can monitor both the engine and the fluid for wear and contamination and should be part of every owner-operator’s preventative maintenance (PM) routine.
As engine oil is pumped throughout different parts of the engine, it picks up vital trace elements of engine component wear and contamination. Oil analysis can monitor your diesel engine’s oil viscosity or thickness, its ability to neutralize acids, and its ability to disperse and suspend soot particles. The test results can reveal deficiencies before they become catastrophic.
There are two fuel conditions that could be found from the analysis:


  • A “rich” condition. A rich condition is when there is too much fuel, usually caused by a faulty injector or fuel pressure regulator and improper air-to-fuel ratios. Testing the engine oil for fuel dilution can help in identifying this condition. Fuel contamination thins the oil and dilutes the oil's additives reducing the oil's film thickness and increasing the risk of metal-to-metal contact.
  • A “lean” condition.  A lean condition is evidence of a much higher concentration of air-to-fuel in the combustion chamber. Oil analysis will show increase in nitration (NOx). A change in the air intake system, Exhaust Gas Recirculation (EGR) operation and cooling system failures can influence this condition

Here are heat issues that could be found from the analysis:



  • Heat expansion and the amount of heat rejection required of the Charge Air Coolers (CACs) in today's EGR engines causes significant levels of stress on an air cooler's aluminum components. Good connections between the turbo charger, CAC, and engine are critical for proper engine performance and fuel economy.  A cracked CAC or leaking hose connection can result in a “rich” condition leading to excessive fuel consumption and/or loss of power.
  • Engine temperature in excess of proper operating range will increase oxidation and nitration and deplete the engine oil's Total Base Number (TBN). Using oil analysis, these changes in oil condition can be identified in their earliest stages.

Oil analysis is an inexpensive diagnostic tool that will help you optimize drivability, improve reliability and save time and money. I recommend using POLARIS Laboratories to conduct your oil analysis.
Want a free oil analysis and one-hour business consultation to review the results? Enter ATBS’ Driver of the Month Contest and each driver chosen will receive a free POLARIS Laboratories Oil/Fluid Analysis and a free one-hour business consultation with yours truly! Just tell them why you are a successful driver and you could be chosen.


Comments (9)

Bill McClusky

I have been in the trucking and construction equipment service industry for 23 years as a service technician, component rebuild specialist (engine, transmission, and axle), service department manager, instructor and consultant. I was a class 8 truck driver for 3 years pulling wet and dry tanks. I have been with American Truck Business Services for 4 years serving as a Business Consultant, Maintenance Consultant, and Instructor.

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To Jeff and Daryl: An engine oil analysis report provides data on the physical properties of the oil, but it also provides the level of accumulated wear metals, additive chemicals, and contaminates. The advanced filtration systems in the newer engines have allowed for longer oil change intervals. I prefer the 25,000 mile test interval mainly due to the depletion rate of the alkalinity additive (TBN) number. If the oils TBN value seems to be holding well after 2 or 3 samples at the 25,000 mile mark and all the other values are normal, then you could start pushing the testing interval out in 5,000 mile increments. You definitely don't want the TBN number to get to low allowing the oil to become acidic.

July 12, 2013 8:48:29 AM

good article bill, I have a dd16 and just did 1st oil change but plan to go synthetic oil next change. is 50000 mi intervals for testing ok or should samples be taken more often?

July 10, 2013 20:18:36 PM

I am 100% sold on doing an oil analysis before I decide what to do at my next PM, Excellant article

June 28, 2013 4:29:53 AM

Such great info to know and learn whether your a onwer-operator of even a company driver.

May 25, 2013 7:06:29 AM

Excellent article, Thanks

May 18, 2013 9:13:49 AM

I struggle with the mechanical issues of a truck. I am not a mechanic. On my last ruck I changed the oil every 20,000 miles even though the engine only required to oil be changed every 45,000 miles. THEN the price of oil changes went through the roof. Oil has improved. My new DD15 reccommnends changing the oil every 50,000 miles. I am going to go with that. Is doing a sample every oil change enough?

May 18, 2013 6:42:57 AM

Thanks Ray, the basic test is a good option if you are changing your oil at the manufacturers recommended intervals. You are correct, the Advanced test is commonly used by those running extended oil change intervals. The advanced test analysis contains three additional tests to determine condition of the oil and additive levels. The TBN (total base number) test determines the amount of alkalinity left in the oil. The alkalinity additive is blended into the oil to neutralize the acids that are generated by the engine combustion process. These acids will deplete the alkalinity over time. Important to have sufficient alkalinity to keep the oil from becoming acidic.Oxidation and nitration tests help determine the condition of the oil.

May 17, 2013 9:33:38 AM

Very good article, Bill!! After looking at the Polaris website, which, by the way, is very overwhelming due to the amount of information there, is the Basic test a good enough option since I have to change my oil every 20,000 miles because of aftermarket warranty requirements? It looks like the Advanced test would be for someone that does extended drains or runs a bypass filter system, is that right?

May 16, 2013 6:45:14 AM

Very good information Bill. Thank you for putting this together.

May 13, 2013 13:36:46 PM