Diesel engine fortune teller? Ever wonder what is really happening inside there?
No, this article is not about Tarot cards, Ouija boards, miracle additives, synthetic oils, hybrids, or electrification. The science of engine oil analysis is real, and it has been around for decades. It is far less expensive than most believe and may save you a fortune in the long run. Testing the life blood of your engine can give you a peek into what is really going on in there. When you pull that dipstick out and see the glitter of metal, or what appears like a misdirected 
chemistry project, it is likely too late.
Oil analysis is more than just the condition of the oil, it also provides element and contaminate levels. Oil and fluid analysis programs are common in some industries, and yet shunned or almost unheard of in others. Some regard these lab tests only for the benefit of extending oil change intervals, but the preventative maintenance savings of an ongoing oil sampling program can far outweigh the low cost and effort that testing requires. The keys are consistency, finding a trusted lab, staying with a specific brand/type of oil and additives, and having the engine oil tested on a routine basis. It is critical that you inform the lab of any major changes in oil, additives, maintenance, or repairs since those can affect the test results. Labs offer various levels of tests and will likely have one predesigned to meet your level of interest. The lab will track the condition of the oil, trace elements, histories, and trend lines. What you may find most important are the lab’s comments and recommendations. If the lab does not provide these, find one that does.
Pictured below is an example of the information commonly reported from the lab. Points of interest are clearly labeled. From these you can decide how in depth you care to investigate the details.
The lab comments and the color coding gives very useful insight into potential problems.
Interestingly, this owner has gone to the effort of implementing an oil analysis program, yet is not using the information. The lab suggests “change oil and filters and resample in a short period”, but the owner opted to further extend the hours/ miles before the final sampling, placing this engine at risk of greater damage.
A few common terms you will encounter in oil analysis are:
Viscosity – the most important trait of engine oil. It is the oil’s resistance to flow and how it reacts to changes in operating conditions (speed, temperature, pressure).
TAN – (Total Acid Number) checks the acid neutralization of the oil. As oil degrades levels of corrosive acids increase
TBN – (Total Base Number) the ability to neutralize acid.
The elements found in the engine oil can indicate possible component wear or pending failure. An experienced lab can better identify the source(s) based on your individual application and lubricates.
To get consistent and accurate results, care must be used while taking the oil sample and getting the correct information to the lab to analyze. To be successful, the process must be clean, controlled, and accurate. The OE service manuals or Oil Analysis Labs have detailed instructions on how the samples need to be gathered and submitted.
Pitfalls you want to avoid:
There are a variety of oil sample kits available, ranging from disposable to reusable pumps, and some engines are equipped with a port in the oil system (prior to the filter) for sampling. A new piece of tubing should be used for each sample, and all components need to be kept free of contaminates.
Engine oil is the life blood of an engine. Take the oil sample with the same level of professionalism your doctor uses while taking your blood sample. Make sure to tell them the meds (additives) used, changes in health history (maintenance) or lifestyle (operating conditions).
People and diesel engines have one thing in common: early detection is the best preventative to bigger problems in the future. My experience is that even with a few days off to recuperate, diesel engines, unlike people, do not heal themselves. Looking into the future through oil sample analysis might just save you a fortune.■
Steve Scott joined the service department at lPD in 1982, working with parts, service and sales for a variety of equipment, diesel, and natural gas engines. Since 2004, he has been the director of product development and technical support for lPD. For more information, email sscott@ipdparts.com.
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