Q&A: What makes oil breakdown in diesel engines

Over time, diesel engine oils break down inside equipment. Toward the end of a drain interval, a lower-quality oil may drastically lose its ability to prevent wear. So what causes this breakdown to happen, and how can you ensure your equipment is protected? Let’s dive in.

What causes a diesel engine oil to break down? 

Oil breakdown is a natural process that occurs in an engine. Things like heat, pressure, and stress are just a few of the factors that cause an oil to break down. Over the life of the oil these factors can lead to dwindling additive reserves and loss of important additives, including the viscosity modifier.

Why are viscosity modifiers important? A viscosity modifier is what makes a multi-grade oil a multi-grade oil. Keeping the oil thick enough at warm temperatures and thin enough at cool temperatures to consistently give equipment the protection it needs.

A big factor behind an oil breaking down is the quality of the viscosity modifier. Simple linear-chain viscosity modifiers, for example, have a tendency to break down quicker and under less heat and stress compared to more complex, radial polymer viscosity modifiers. 

What could happen to my fleet if I don’t use a quality oil?

Using a poor-quality oil means using an oil that does not have additives that can hold up between drain intervals – including a viscosity modifier. When a viscosity modifier breaks down, an event known as shearing, the oil will lose its viscosity and become too thin to protect critical components. This can lead to components breaking down and costly repairs and downtime.  

How can I avoid issues and keep my fleet protected?

To keep your engine protected throughout the drain interval, it’s important to use a diesel engine oil with a viscosity modifier that has a good shear stability – one that won’t break down before the oil is drained. 

Products like our full synthetic Cenex^® Maxtron^® Enviro-EDGE^® and semi-synthetic Maxtron DEO contain a viscosity modifier called EnduroVis^™. This viscosity modifier has a unique star shape that stays intact as it moves through the engine. The EnduroVis viscosity modifier makes Cenex Maxtron Enviro-EDGE and Maxtron DEO up to seven times more shear stable than the traditional linear viscosity modifiers on the market today.

Find your local Cenex dealer and learn more tips to optimize your operation.