Today’s challenges on modern fleet maintenance are becoming more demanding, predominantly defined by changes in equipment, regulatory controls, and the constant pressure to keep the fleet on the road for longer to increase profitability. A critical step in any maintenance programme is the use of lubricating oil, the primary purpose of which is to limit friction by creating a thin film between the moving parts to prevent potential damage or wear. A better understanding of the numerous types and specifications available on the market can go a long way to help fleet managers make smarter choices in their selection of oils. However, today’s commercial lubricants from engine oils to hydraulic fluids – contain more technology than many people realise.

Lubricants and their composition

Lubricants do far more than preventing wear and tear on moving components. Due to operating conditions, these components accumulate dust and dirt over time. As lubricants move through the engine or other machinery, they collect and remove such fragments and particles to ensure the moving parts don’t jam or become clogged. They are also designed to clean, cool, and protect the engine thereby enhancing the engine’s working life. 

Lubricants have 2 main components – the base oil and additives (viscosity modifiers can fall in this category)…not all lubricants have viscosity modifiers. In most instances, the base oil makes up between 70 percent and 90 percent of the lubricant’s overall composition, depending on its formulation. Base oils are classified into five categories – from Group I to Group V – each of which has different benefits and quality implications. 

Base oils can be mineral (conventional), synthetic or semi-synthetic. Groups I, II and III are all mineral oils with increasing severity of the refining process, whereas synthetic oils are typically created from chemically modified materials such as petroleum components, but the base material is almost always distilled crude oil. It’s also the most expensive oil and is usually reserved for specialist applications. Semi-synthetic base oils are a blend of conventional and full synthetic oils. 

Commercial lubricants have distinctive additives depending on the functions they need to perform. These additives could be in the form of detergents whose primary function is to keep engine surfaces clean. The detergent is also alkaline, and enables it to neutralize acidic combustion by-products, which would corrode engine components. The amount of alkalinity in an engine oil is measured by its Base Number (BN). Dispersants prevent contaminants and particles in the oil from joining into larger particles, and by preventing them from re-depositing on the surface, the dispersant keeps contaminants in suspension until the oil is changed. Additives generally make up 10-25 percent of a lubricant, including engine oils.

The viscosity modifier is a high-molecular polymer that changes the temperature dependence of the viscosity of the lubricant. In other words, they enable lubricants to function more efficiently over a wide range of temperatures. Without a viscosity modifier, for example, a lubricant that runs thin in the summer will run thick in the winter. 

Engine oils, also referred to as “motor oil” are designed to lubricate internal combustion engines. 

The owner’s manual or maintenance manual will inform you which specification, type and viscosity grade of oil the manufacturer specifies. Typical viscosity grades include SAE 10W40 or 15W40 for diesel engines and SAE 5W30, 5W40, 10W40 and 15W40 for petrol engines.

Choosing the right oil

Properly lubricating the inside of a heavy-duty diesel engine requires more than just creating a protective film. That’s why understanding how lubricants work will help fleet operators select the best product for their needs. 

Yet, selecting the right lubricant for your fleet doesn’t have to be rocket science. Consulting OEM specifications is a good start, while a reputable commercial lubricant supplier, such as Astron Energy, can advise on the best solution for the most challenging conditions. Astron Energy provides finished lubricants and premium base oils to commercial, consumer, and industrial users throughout the country.