Alleviating the effects of idling engines

Vehicles involved in crushed stone, sand and gravel mining work under tough conditions, ones in which they must start and stop regularly. This, of course, can increase engine wear.

In a demanding environment where mining fleets are expected to run reliably, efficiently and safely, unplanned maintenance and downtime can have a significant effect on a business’ bottom line.

Achieving marginal gains is, therefore, crucial for fleet managers who need to consider all of the factors affecting equipment performance, including the impact engine idling can have on reliability and fuel economy.

The cost of idling engines

Mining machinery can spend a large amount of time with an idling engine.

Komatsu, for example, suggests that an average machine’s idle time is 40 percent. Given the multi-stage process of aggregate mining, you can assume this figure is likely higher for the aggregate industry.

Just an hour of idle time is equivalent to about 25 miles of over-the-road driving and can have hidden impacts on the engine. Idling can alter the combustion process by increasing the likelihood that oil temperatures will drop below 200 degrees. Water can accumulate when this process is altered, leading to the formation of acids in the engine oil, which, in turn, increases the likelihood of fuel dilution.

Prolonged idling will accelerate engine wear and increase the need for oil changes, even if the vehicle’s hour meter displays or maintenance schedule suggests differently.

Idling engines can also use considerable fuel. It is estimated that a large diesel engine can consume as much as one gallon of fuel every hour it idles. Combating this problem can be difficult. Lubricants can offer protection from idling while also improving fuel economy.

The role of lubricants

A high-quality, heavy-duty engine lubricant can reduce pumping and spinning losses while minimizing metal-to-metal contact between engine components. This helps protect the engine’s vital hardware while also enhancing performance and improving fuel economy.

For heavy-duty vehicles in the aggregate industry, American Petroleum Institute CK-4 oils are now particularly relevant. Offering increased shear stability, this oil specification protects against both oxidation and aeration.

Off-highway mining machinery can take on more air in their engine oil than usual, so aeration control is important. This is especially the case at the bearings, where a robust oil film is required for protection.

Along with the extent of idling that an engine experiences, operators should account for the region and climate their machines operate in. These factors can affect the rate of engine wear when not properly lubricated.

For fleets operating in colder climates, different oil requirements will be appropriate – oils that are designed to provide protection in colder climates are marked with a “W” (denoting winter) that features after the Society of Automotive Engineers (SAE) grade. Fleets in warmer areas are more suited to heavier oils like the SAE 30 or 40 grades, which resist the breakdown that occurs at high temperatures to ensure adequate flow and engine protection.

Aggregate mines operate across the globe, so it’s also important to consider the viscosity of oil that determines its ability to flow. Too high of a viscosity may mean the oil resists easy movement, delaying lubrication, which will affect the protection of the engine and may result in increased engine wear.

To ensure oils can lubricate critical components, even when operating in the coldest operating conditions, it’s useful to look for industry standard tests such as cold crank viscosity (CCS) and low temperature pumpability (MRV).

Understanding the impact

Implementing a used oil analysis program can highlight if oil needs to be changed earlier than usual. By bringing attention to maintenance issues before they turn into serious problems, managers can save on repair costs, as a used oil analysis will reveal the hidden impact idling can have.

An oil analysis can also help to extend oil drain intervals, a step that should only be undertaken based on recommendations from an original equipment manufacturer’s manual and advice from technical experts. Taking steps contrary to these recommendations may invalidate any warranty coverage if damage or engine failure occurs.

Typically a three-step process, used oil analyses involve taking a representative sample from the equipment before sending the sample to a qualified used oil analysis lab and then interpreting and acting on the recommendations of the results. Additionally, performing analyses at regular intervals helps to generate performance databases that can be used to establish data trends.

Scheduling this process allows maintenance plans to be adjusted in advance, meaning it can be managed in line with planned downtime, making the overall maintenance process more efficient.

Final thoughts

Engine idling can have a significant impact on aggregate operations. By selecting high-quality heavy-duty lubricants, fleet managers can improve the reliability of their fleet while reducing any unplanned downtime.

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Brian Humphrey is OEM technical liaison at Petro-Canada Lubricants.