The lazy days of summer don't typically apply to contractors. For many, summer usually means more jobs, longer work days and, if you're not careful, more heat-related breakdowns.
As ambient temperatures climb to 90° to 95° F and above, you need to be aware of potential problems the extra heat can wreak on your equipment, in particular, to lubricants and fluids that keep equipment running smoothly and efficiently.
"Extra stress is placed on lubricants whenever equipment is operated for extended periods at above-normal temperatures," says Allan Perry, certified lubrication specialist, ConocoPhillips, 76 Lubricants and Conoco brands.
"Contractors need to make sure they use the correct viscosity grade recommended for those operating conditions, and that they do not overextend drain intervals."
Typically, as the temperature rises, so should the viscosity level of the oil, advises Dan Arcy, technical marketing manager at Shell Lubricants. "As a lubricant heats up, it thins out," he explains. "That's why your engine will need a thicker (more viscous) product in hotter temperatures to provide adequate lubricant thickness."
The same thought holds true for greases, says Mark Betner, heavy-duty product manager for CITGO Petroleum Corp. Use greases with heavier base oils that tend to stay put under shock loads and reduce water washout in the summer. Also, greases that contain 3% to 5% molybdenum disulfide (moly) will help reduce wear in heavy contamination and high load conditions. It may be necessary to use a winter or NLGI No. 1 grease in colder weather to maintain pumpability and flow.
"So often we think of engines during high temperatures, but the hydraulic systems can benefit from multigrade hydraulic fluids by maintaining improved power transfer efficiency and cycle times as compared to single-grade hydraulic fluids," he says. "The multigrades may also provide better cold temperature performance."
"These high viscosity index oils will show less change in viscosity with temperature than low viscosity index oils," adds Perry. "In order to maintain adequate bearing oil film thickness, an OEM will typically recommend using a higher viscosity oil at higher temperatures."
Equipment manufacturers list recommended oil and grease viscosity levels for certain ambient temperatures in their owners' manuals. Oil supplier representatives are also a helpful resource in determining the proper engine and hydraulic oils, greases, etc., for your specific operating condition.
A motto to live by
All of these fluids are designed for optimum performance at certain ambient temperatures. To ensure your summertime lubricant selections continue to perform as designed, follow the basic motto: keep it clean, keep it dry and keep it cool.
Keep it clean
This applies to the inside as well as the outside of all your machines.
When dirt and mud build up under the hood (on components such as radiators, engines and reservoir tanks), they act as insulators, making it more difficult for heat to dissipate. In the case of hydraulic systems, this is especially important since most don't have any built-in coolers. They rely on ambient heat transfer to cool the fluid.
On the outside, concentrate on keeping the fill cap area clean to minimize the potential for admitting dirt and debris into the reservoir when you unscrew the cap. And when applying grease, keep any excess lubricant off of the equipment because it can attract dirt that can eventually work its way into the bearings and cause wear.
Keep it dry
"Dirt and water are two main enemies of lubricants," says Dave Tuohy, off-highway specialist at ChevronTexaco. "Water is detrimental because it prevents the lubricant from maintaining its viscosity, and it changes the lubricity element of that lubricant. Plus, it wants to churn up into air bubbles. When it does that, it doesn't lubricate the parts correctly, which in turn creates more friction and heat."