Canadian Mining Journal


The hidden impact of idling engines

Monitoring reveals the pitfalls

By some estimates, a machine’s average idle time is about 40%. CREDIT: PETRO-CANADA LUBRICANTS

Heavy duty equipment in the mining industry operates in some of the world’s most extreme environments, often with the additional challenges posed by cold weather conditions. Added to this, fleets are expected to run reliably, efficiently and safely on sites that are live 24 hours a day, seven days a week, and where any unplanned down time can result in a significant impact to a business’s bottom line.

Marginal gains in reliability and fuel economy are therefore crucial for fleet managers who need to consider all the factors that affect equipment performance, including the impact that prolonged engine idling can have.

A focus on engine idling

Mining machinery can spend considerable time onsite with an idling engine, with manufacturer Komatsu, suggesting that a machine’s average idle time is 40%. However, given the nature of the industry, it’s safe to assume that this figure may be even higher.

An hour of idle time is equivalent to about 40 km of driving, and often has a hidden and overlooked impact on equipment engines. Idling can alter the combustion process by increasing the likelihood that oil temperatures will drop below 100° Celsius. This can result in the accumulation of water and increase the formation of acids in the engine oil, as well as increase the risk of fuel dilution. Prolonged idling can therefore accelerate engine wear and the need for oil changes, even if the vehicle’s hour meter or maintenance schedule states differently.

Idling can use considerable fuel – it is estimated that a large diesel engine can consume up to 4 litres of fuel for each hour it is left idling. So how can lubricants offer protection for engines that idle while also providing fuel economy for maintenance managers?

Lubricant’s vital role

Lubricants reduce pumping and spinning losses as well as minimizing metal-to-metal contact between moving components.

This protects the engine’s vital components and enhances its performance, which can lead to improved fuel economy.

For those within the heavy duty off-highway industries such as mining, API CK-4 oils are of particular relevance. These offer improved resistance to oxidation and aeration, along with increased shear stability. Off-highway engines can entrain more air than usual in their oil, so improved aeration control is important.

This is crucial at the bearings as they require an oil film to protect them.

Mining equipment also operates in some of the coldest conditions so it’s essential to select an oil that benefits from a lower viscosity at lower temperatures. API CK-4 SAE 10W-30 and 5W-40 oils offer this and can move more easily throughout the engine and flow faster, preventing engine wear during start-up.

This is also an essential benefit for engines that idle regularly, as it can reduce the work rate of the engine.

Modern low viscosity oils enable easier cold starts, which supports the ability for the engine to be turned off and reduce idling.

To help neutralize any acid that builds up during prolonged idling, the oil selected should also be able to maintain its Base Number.

Oils that effectively combine these properties offer enhanced protection and can help improve reliability to reduce unplanned downtime for mining equipment. However, before selecting a lubricant, it’s crucial that the product is based on the original equipment manufacturer’s (OEM) recommendations, as outlined in the owner’s manual.

Unveiling the impact through monitoring

A used oil analysis program can highlight if oil should be changed earlier than normal and bring to attention maintenance issues before they become serious and expensive to repair. This is extremely beneficial for uncovering the hidden impact that idling can have on heavy duty mining machinery.

Oil analysis can also support the extension of oil drain intervals.

This should always be supported by recommendations from the OEM manual and advice from technical experts; particularly when it comes to considering if and how to extend drain intervals.

It’s important to reference the OEM manual, as going against recommendations could invalidate any warranty coverage if damage or engine failure occurs, which could be expensive to repair.

Oil analysis is typically a three step process: taking a representative sample from the equipment in question, sending the sample to a qualified used oil analysis lab, and interpreting/acting upon the recommendations of the results. This is most effective when performed at regular intervals, as it allows for a performance database to be generated, and for trends to be established and identified. For the mining industry, where unplanned downtime results in a direct impact on the business’s bottom line, this scheduling allows for maintenance plans to be adjusted in advance and managed in-line with any planned downtime.

The impact of engine idling can be significant for off-highway engines, especially those in the mining industry where equipment is under pressure to operate 24 hours a day, seven days a week in extreme conditions. By selecting a tough heavy duty lubricant that can perform under these conditions and provide enhanced engine protection, fleet managers can benefit from improved reliability while reducing unplanned downtime.

Brian Humphrey is OEM Technical Liaison with Petro-Canada Lubricants. For more information, visit and

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