A study in sand_empty road desert sunset

A Study in Sand (Part 3)

A Study in Sand (Part 3)

May 15, 2020

In the third and final article in this series, we examine remedial actions which can reduce internal combustion engine component damage as a result of sand or dust ingress.

In recent years, extended oil drain intervals have increased in line with industry and original equipment manufacturer (OEM) specifications. However, in harsh operating environments such as the Middle East, Africa and other desert type terrain, frequent oil changes are seen as the primary method of keeping dust contamination at manageable levels to protect the engine. Extending oil drain intervals is likely to result in a higher concentration of sand or dust found in engine lubricants. Irrespective of the robustness of the base oil and additive in a formulation, engine lubricants cannot completely prevent dust related wear to engine components. Conversely the question remains—are some engine lubricants are better than others in terms of reducing sand or dust related wear?

In previous articles, we established that journal bearings can be severely affected by sand or dust-related wear. These components were studied further to observe the wear using different types of engine lubricants.

There is a school of thought, traditionally held in emerging markets, that heavier viscosity lubricants are more effective at preventing wear caused by abrasive particles. To this end, two monograde lubricants of different viscosity grades (SAE 20 and SAE 40) were tested in a bespoke valvetrain rig in which bearing wear was measured.

No significant differences in wear were observed, indicating that using higher viscosity monograde lubricant does not offer improved protection against wear from sand or dust in an engine (see Figure 1).

Fig 1_Average exhaust valve camshaft journal bearing wear

Figure 1

 

The test was then repeated using an SAE 15W-40 multigrade lubricant formulated with a performance polymer. The kinematic viscosity at 100°C and high temperature high shear viscosity (HTHS = 4.1 mPa.s) were kept consistent with the SAE 40 formulation. This time, a noticeable reduction in average exhaust valve camshaft journal bearing wear was observed (see Figure 2).

Fig 2_Average exhaust valve camshaft journal bearing wear

Figure 2

 

It is well known that performance polymers, historically known as viscosity modifiers, impart significant benefits to an engine lubricant. Cold flow performance at start up and engine protection at the high operating temperatures experienced in modern engines are well founded and documented. However, the evidence here shows that the inclusion of a performance polymer in an engine lubricant formulation actually helps reduce sand and dust related wear. The experiment demonstrated a significant 40% reduction in average exhaust valve camshaft journal bearing wear.

The experiment was repeated using a range of performance polymers. Each time a significant reduction in average exhaust valve journal bearing wear was observed compared to the monograde formulation results. One innovative performance polymer solution provided a 70% reduction when compared to the monograde reference. This is novel technology for ultra low viscosity lubricants. Tests have proven that when force is exerted the lubricant resists to maintain a molecular boundary between moving parts to ensure that damage does not occur.

Our View

Sand and dust do enter an engine environment and are capable of causing damage to components, especially exhaust valve journal bearings. Vehicles and machinery working in desert climates and off highway vehicles, operating in quarries and mines where sand or dust ingress is a day-to-day reality, are particularly susceptible to this problem. When it comes to controlling silica concentrations, there is no substitute for frequent lubricant changes and vehicle maintenance.

However, combining these practices with the use of a modern multigrade lubricant formulated with a performance polymer has been shown to provide enhanced protection against sand and dust related wear. This can directly translate to reduced maintenance costs and increased uptime for end users.

In addition, a video explaining the impact of sand and dust ingress on engine performance and how to address with a lubricant solution is available here.

For more information on how sand and dust can affect your vehicle’s engine, contact your Lubrizol representative.

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