How Do Hot Temperatures Impact Lubricants?

One of the main concerns for fleets and owner-operators working in hot environments is a decrease in lubricant film thickness due to lower viscosity. The viscosity of an oil is crucial as it dictates its ability to form an oil film to protect moving engine parts from excessive contact. If the oil’s viscosity is too low, the oil film thickness may be too low which could mean that the engine parts aren’t being protected effectively, causing an overheated condition. This can cause serious operational problems such as a breakdown of the oil film, reduced power, increased oxidation rates, and fuel economy losses due to oil thickening.

It is critical that the operating temperature of the equipment is taken into account when selecting an oil. A warm climate often necessitates a heavier engine oil such as an SAE 30 or 40 grade; one able to resist the breakdown that comes with higher operating temperatures by ensuring proper and adequate film thickness and the protection of critical engine components.

SAE classifications values that do not include the “W”, define oil grades designed for use at higher temperatures.  The second number in the viscosity rating – the “40” in 10W-40, for example – means the oil will have a thicker film at high temperatures than one with a lower second number.

Planning and preparation is key

Regardless of the climate and conditions, a fleet owner-operator is working in, it’s crucial that they have prepared and considered not just their choice of lubricants, but multigrade hydraulic, driveline, and gear oils too to ensure all engine components are protected. Operators should also be regularly checking coolant condition and batteries to ensure engines are running safely and efficiently, no matter the weather or time of year.