Nitration – How an Engine Lubricant Suffers from it.



If you would have seen Viswa Lab’s Lubricant analysis trend report, one must have wondered and definitely noticed a parameter called “IR-Nitration”.

Let us not worry too much about IR – as it simply stands for Infrared or a test method by which Viswa Lab quantifies the Nitration in Absorption Units (au).  But, the main thing to worry and understand is the process of Nitration and the mechanism by which a diesel engine suffers a damage from it.

In simple terms, Nitration is a degradation of the oil that results from a reaction of the oil with gaseous NOx created during combustion.

Oils can break down in a variety of ways.  One of the most prevalent ways is the degradation of the base oil.  Oxidation is perhaps the most widespread form of this degradation, but nitration is also common, especially in some engines.

Nitration is the breakdown of the base oil caused by the reaction of oil molecules with different compounds to form nitrous oxides and other nitrogen compounds.  This can occur in a number of manners, but the most frequent is due to combustion issues.

As nitration progresses, more nitrous oxide compounds are formed, which can lead to an increase in the acidity of the oil, the likelihood of lubricant malfunction and subsequently the wear of internal engine surfaces.


Viswa Lab tests an engine lubricant for nitration through a test known as Fourier transform infrared (FTIR) spectroscopy.  In this test, an infrared beam is passed through the oil and absorbed at different wavelengths, which correspond to different contaminants and constituents within the oil.  This test provides reliable information on things such as soot, nitration, oxidation, fuel, glycol and water.

FTIR is most effective when a reference sample is used for comparison.  It is for this reason, Viswa Lab recommends to land a fresh oil sample along with a batch of used lubricants so that the fresh oil value can be used as a reference or base line.  The used oil test result is compared with the fresh oil test result and the degree of oil degradation is determined.  Viswa Lab flags an oil abnormal based on a deep study on various such intrinsic parameters which are usually classified under three major groups:

  1. Oil Chemistry
  2. Oil Contamination
  3. Wear Metals

By monitoring the base oil health as well as additive health, you can ensure that you are changing the oil on time before the oil goes bad or excessive wear occurs inside the engine.

Source: Viswa Lab & Noria

We thank Viswa Lab for providing us with a sample Lubricant analysis report.  This report is a sample and for representation purpose only.  The values are random to match the content of this write-up and may not be an actual test result.