36 n BEARINGS, BELTS AND CHAINS March 2026 www.drivesncontrols.com Which is the better: oil or grease? According to the Siemens report, The true cost of downtime, the annual cost of an idle production line at a major automotive facility has surged to $695m – 1.5 times more than five years ago. In heavy industry, downtime now costs $59m annually – a 1.6-fold increase since 2019. These costs underscore just how critical it is to prevent avoidable equipment failures – but how often do production managers consider the critical role of industrial bearings in ensuring equipment longevity? When using industrial bearings, few decisions are as important as the choice between grease and oil lubrication. Both lubricants share the same fundamental purpose, and each plays an essential role in reducing friction, minimising wear and extending bearing life. But the conditions in which they operate best are very different. Making the wrong bearing lubricant choice can lead to overheating, premature failure or unplanned downtime. To avoid these outcomes, let’s look at how to choose the best lubricant – and reduce the cost of downtime. Where grease excels Grease has a thicker consistency than oil. It is usually a base oil suspended in a soaplike thickener, which helps it stay in place more easily – especially in vertically mounted or hard-to-reach locations. These characteristics make grease ideal for applications such as electric motors, conveyor systems or food-processing equipment where protection from washdown or particles is essential. Grease also acts as a sealant, helping to keep out dirt, moisture and other contaminants. It is typically easier to apply and less prone to leakage, which makes it a costeffective solution for sealed or shielded bearings that aren’t maintained regularly. Grease is often the preferred choice in applications that need simplicity, longer service intervals or operate in environments where lubricant retention could be a challenge. However, grease also has its limitations. It doesn’t dissipate heat as efficiently as oil and can break down faster in high-speed or high-temperature environments. Excessive heat can cause the thickener to degrade, reducing lubrication effectiveness and potentially damaging the bearing. When oil is a better fit Oil is often favoured in high-speed or lowtorque applications where better cooling and continuous circulation are needed. Unlike grease, oil can be pumped, filtered and monitored as part of a closed lubrication system, allowing contaminants to be removed and fresh lubricant to be supplied continuously. Typical examples include gearboxes, machine tools and high-speed spindles. In these cases, the superior heat transfer properties of oil reduce the risk of thermal damage and prolong bearing life. Oil also reduces friction in many situations, making it well-suited to precision applications that demand tight tolerances and consistent performance. That said, oil systems are more complex and require careful design. They need pumps, reservoirs, filtering and regular monitoring. Some applications require a continuous oil mist or spray, adding to maintenance requirements and cost. Oil systems are also less effective in vertical or exposed environments where leakage or oil migration can become a problem. Several operating parameters should guide the decision between grease and oil lubrication, each with a direct impact on bearing performance. Speed is one of the most critical considerations. As rotational speed increases, so does friction and heat. In many high-speed applications, oil is preferred for its ability to circulate and dissipate heat more effectively than grease. Temperature is another key factor. In environments where bearings are exposed to elevated operating or ambient temperatures, oil typically provides better thermal stability and cooling capacity, with much less resistance than highWhile bearing failures are relatively rare, improper lubrication remains a key contributor. Choosing between grease and oil isn't easy. Chris Johnson, managing director of SMB Bearings, explores the advantages and limitations of each approach.
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