Shell Rotella® Guide to Extreme Temperature Engine Protection
To maintain fuel-efficient vehicles, it’s crucial to understand an engine oil’s resistance to flow – whether it’s 200° or -30°F – and its impact on product choice.
Your business is a well-oiled machine that operates best when all its parts – people, processes, physical plants and fleet – work seamlessly.
A plant’s manufacturing line brought to a grinding halt by equipment issues related to a malfunctioning gearbox creates supply chain issues. And planes, trains, and automobiles stopped in their tracks by subarctic weather put people’s lives and livelihoods at risk.
Without knowledge of the impact of temperature on oils, equipment failures are not uncommon. Just a single hour of downtime can result in losses of hundreds of thousands of dollars. So, an understanding of all the different impacts of temperature is necessary to help maximize the life of an oil and your equipment.
How temperature impacts wear protection
Although two metal surfaces that come into contact in a machine may look smooth, magnification would reveal a scene that more closely resembles a mountain range, with peaks and valleys. The ‘peaks’ are called asperites.
It’s these asperities that come into contact as metal parts slide, unless there’s a proper fluid film. The oil between two metal parts that reduces friction between them, the fluid film, needs to be thick enough to separate the two surfaces even under load.
However, it shouldn’t be so thick that the parts struggle to move.
Know the right oil viscosity
The engine manufacturer will recommend the optimum oil viscosity to use based on the operating conditions of the vehicle. And synthetic blend and full synthetic lubricants offer additional protection for the engine at high and low temperatures.
For instance, if you have two metal plates that are moving against each other in a hot environment, a low-viscosity oil may not provide the ideal fluid film, resulting in metal-to-metal contact. This increases wear and heat while reducing component life.
Now, if you take those same two components and use a lubricant with a viscosity that’s too high, there may be a drag effect at operating temperature that increases friction. This is an inefficient use of the oil, potentially resulting in unplanned time delays, extra energy usage, and costs.
Why higher temperatures reduce oil life
The Arrhenius rate law states that with every increase of 50°F in a lubricant’s base temperature, oil life is halved. “We also see the rate of oxidation about doubles,” asserts Dr Jason R Brown, Global Technology Manager for Heavy Duty Diesel Engine Oils at Shell. “It’s a very significant difference for what seems like a small jump in temperature.”
It’s possible to see large temperature swings even within the United States. Imagine travelling south to north, picking up an order in Houston where it’s 55F.
By the time you get to Ohio you could be driving in sub-zero temperatures, which can make your engine oil thicken. The thicker it is, the less efficiently it flows to critical engine parts, potentially causing wear and tear at start-up.
Original equipment manufacturers (OEMs) provide oil viscosity guidelines for each vehicle, based on ambient temperature, application conditions, etc. These should always be followed – to help protect your engine.
By understanding all the critical temperature-related elements that can impact oil viscosity, functional decision makers, drivers, and engineers can create a ‘well-oiled’ plan that keeps assembly lines and supply chains moving, and gears and pistons humming… whether the temperature’s too hot, too cold or just right.
| Current Oil Temperature | Twice-the-Life Oil Temperature |
| 300°F (149°C) | 282°F (139°C) |
| 275°F (135°C) | 257°F (125°C) |
| 250°F (121°C) | 232°F (111°C) |
| 325°F (107°C) | 207°F (97°C) |
| 200°F (93°C) | 182°F (83°C) |
| 175°F (79°C) | 157°F (69°C) |
| 150°F (65°C) | 132°F (55°C) |
| 125°F (52°C) | 107°F (41°C) |
Why higher temperatures reduce oil life, from TOO HOT, TOO COLD, JUST RIGHT: The Effect of Temperature on Lubricant Viscosity by Shell.
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