Regular Engine Oil Analysis: How it Impacts the Performance of Engine?

Given that engine oils are subjected to extensive variations in climate and stress when in use, the need for engine oil analysis has become increasingly significant in recent times. Besides commercial vehicles, industrial machineries require heavy-duty motor oils (HDMOs) for proper lubrication of their internal components.   

With HDMOs serving as a line of defence for engine components to protect them from adversities like accelerated wear or rough operation, they must be in optimal condition during running cycles. That’s what is ensured by engine oil analysis, a routine practice which studies the oil’s health and contamination status.

Common Tests Performed in Engine Oil Analysis

With time and the continuous operation of an internal combustion engine used in vehicles and industrial machinery, the properties and health of engine oil degrade gradually. Contaminants such as combustion by-products, sludge, fuel, water, coolant, and soot can further contribute to the degradation of engine oil, affecting their viscosity (thickness of flow), life and lubrication properties.

Across three categories – fluid properties analysis, contamination analysis, and wear analysis, the engine oil is tested for these aspects:

Viscosity

Viscosity readings must closely match the specified grade; significant differences may result from oxidation, contamination, or mechanical shearing of the oil during prolonged use.

Total Base Number (TBN)

It is a measure of alkaline content in the engine oil using titration methodology. The additives in engine oils will neutralise with acids formed during combustion. If the TBN drops significantly during engine oil analysis (less than 50 per cent of the original value), it is an indication of abnormal operating conditions, which might also require replacement of the oil.

Total Acid Number (TAN)

Just like how TBN measures alkaline content in the engine oil, TAN measures the relative acidity in it. Also measured by titration, TAN is used to detect the oxidative degeneration of the oil. A sudden increase in TAN (an increase of 2.0mgkoh/g than the original value) also indicates abnormal operating conditions, requiring engine oil replacement.

Water/Moisture

A common contaminant of engine oil, water usually enters the engine oil as a by-product of fuel combustion or coolant leakage. Significant water penetration in the engine oil accelerates the wear of the oil and can even lead to engine seizure. The water content in the engine oil detected by titration in the tests should not exceed 0.5 wt%.

Oxidation and Nitration

Oxidation in engine oil is typically detected using infrared analysis and is quantified by the level of oxidation by-products, expressed as an oxidation number in Abs/cm. Similarly, nitration refers to the concentration of NOx compounds in the oil, also measured in Abs/cm. Elevated oxidation values indicate significant oxidative degradation, which promotes deposit and sludge formation and consequently shortens oil life. High NOx content signifies increased nitrous acid production within the oil, potentially diminishing additive effectiveness and accelerating sludge accumulation.  

Elemental Analysis

Elemental analysis is employed to detect residual additive components, wear metals, and contaminants present in oil. The inductively coupled plasma (ICP) technique is commonly used to quantify the various elements within the oil sample. In this process, elements are ionised at high temperatures, and the emitted light from each element is measured and identified using specialised instruments and software. This test requires samples in liquid form and cannot detect particles larger than 3 microns.

Soot

Soot refers to the accumulation of carbon deposits or contaminants in engine oil. Excessive soot content in the oil can increase wear rates and lead to sludge formation. Soot levels are usually measured using infrared or photometric techniques, each providing results on a different measurement scale.

Fuel Dilution

Fuel dilution refers to the ingress of fuel into the lubricant as a result of inadequate combustion chamber sealing or suboptimal engine combustion. While minimal fuel dilution (below 2%) is generally considered acceptable, higher concentrations can be problematic, potentially compromising the viscosity of engine oil.  

Particle Count

This test measures the quantity and size of particles present in the lubricant. Fewer and smaller particles contribute to longer oil life and promote smoother oil flow by reducing blockages in oil crevices and minimizing hot spots.

Ferrous Particle Count

This method evaluates the concentration of ferrous (iron) particles in engine oil, which originate from the wear of internal surfaces and components. The measurement is conducted using integrated magnetometers or a direct-read ferrography system.

Wear Debris Analysis

This analytical technique separates magnetic wear particles from the engine oil and collects them in a glass slide (ferrogram). It is used to study the characterisation of the type of wear and its sources.

Advantages of Engine Oil Analysis

All these tests performed on the engine oil aim to assess the current health of both the lubricant and the machinery components it serves. This analysis can diagnose lubricant properties, detect contamination, and identify wear patterns, offering long-term benefits. Other benefits include as below:

Predictive Maintenance

Over time, engine oil loses its beneficial components, which can affect its ability to lubricate properly. By analysing engine oil, we can evaluate how well it is currently performing and predict its future effectiveness during the rest of its life span. This process helps prevent unexpected breakdowns and costly repairs.

Usage Management

Periodic oil analysis optimises the frequency of oil replacement based on actual usage conditions, rather than entirely relying on fixed intervals. It eventually helps in saving unnecessary costs in oil replacement.

Reliable Functioning of the Engine

An in-depth engine oil analysis is capable to provides the condition and health of the engine, it indirectly identifies the working potential, while monitoring the health of the engine to achieve better efficiency.

Understanding the Core of Wear

The engine oil analysis detects the amount or number of wear-causing elements and potentially identify the source of wear. This helps understand the component wear rate in the engine and if replacement should be scheduled to prevent unwanted engine malfunction.

Caltex LubeWatch Oil Analysis Program: How is it an Effective Solution?

An advanced and comprehensive engine oil analysis program, “Lubewatch” by Caltex, has been instrumental in monitoring the engine’s functionality and maintenance work. It eventually helps reduce the downtime, maintenance costs and even the risks of engine failures.

Caltex LubeWatch Oil Analysis Program is a collection of six basic test packages and various testing procedures, with its data used for reliable interpretation.

Conclusion

India's tough climate and heavy usage create challenges for engines, but regular engine oil analysis reduces their vulnerability. Proactively checking engine oil improves performance, reliability, and lowers maintenance costs.

FAQs

Why is oil analysis important?

Engine oil analysis helps lower maintenance costs, optimise equipment life, maximise oil replacement intervals, minimise equipment downtime and schedule preventive maintenance more efficiently.

What are the applications of oil analysis?

Engine oil analysis is a tool for predictive maintenance of engines, equipment health monitoring, optimisation of oil change intervals, reducing waste, maintenance cost reductions, proactive troubleshooting, quality control and environmental protection.