Oil flow is critical at startup. "Most of the normal wear occurs at cold startup," says Ewing. "The quicker you can get the oil flow to all of the moving parts, the better off you are."
Mark Betner, heavy-duty product manager at Citgo, agrees, adding, "The better an oil flows in these conditions, the better the wear protection, along with reduced stress on batteries and starters."
Oil flow at a given temperature is determined by the viscosity. "It is important to check with the OEM; typically it provides viscosity recommendations for given operation temperature ranges," says Gerig. "If you are unable to pre-warm the engine prior to a cold start up, using the correct viscosity grade will provide some wear protection."
Lighter viscosity engine oils also increase cold start capabilities. Batteries lose cranking power in cold weather and the oil thickens. "The crankshaft is trying to turn through the oil," says Arcy. "So if you go with a lower viscosity oil, the resistance will be less and it will take less energy for the starter or battery to turn it over. We had one [customer] that reduced the remote starters they were having to use on some of their equipment by switching to a lighter viscosity product."
With multigrade oils, it is particularly important to select the correct grade. "The W associated with multigrade oil can make a difference in cold temperature fluidity and borderline pumping temperature," says Betner. "Oil such as 10W-30, 10W-40 or, better yet, 5W-40 can make a considerable difference in cold temperature flow, demand on batteries and starters and, ultimately, film protection of moving parts at startup."
Synthetic oils offer the advantage of a larger operating temperature range than mineral oils. For example, consider a synthetic 5W-40 engine oil. "In most cases, you are going to be good down to -20° F all the way up to 120° F," says Arcy. "So you have a really broad range with a synthetic."
In many instances, this will eliminate the need to change oil strictly based on the ambient temperature. But the cost of the synthetic can be three or four times higher than a conventional oil.
"There is always the alternative to stay with a conventional-type product and drop down a viscosity grade," says Ewing.
"The main thing you have to watch in the cold weather is the cold temperature flowability. There are several tests that the industry uses to make sure you get the W rating."
Unlike engine oils, gear oils and final drive oils usually can't be warmed up prior to operation, which amplifies the need for the correct viscosity. "Typically, a dozer or grader will be started and just take off without considering that the planetary and final drive gear sets are still cold," says Ewing.
In applications where the oil may not be changed seasonally, and there is a wide temperature range of operation, a synthetic may provide the best solution. "For example, the difference between an 85W-140 mineral type gear oil and a 75W-90 synthetic gear oil can be as much as 50° F of ring and pinion protection in cold weather," says Betner.
Also don't forget to check the condition of gear and final drive oils. "If you do construction work during the summer where you know the equipment has been subjected to a lot of water, be sure the reservoirs and the drives are dry," says Ewing.
If equipment will be operated in the winter, the choice of hydraulic fluid grade is also critical, and the use of auxiliary heaters can add another layer of protection.
"Hydraulic systems can undergo cavitation, an air-binding condition resulting from lack of oil flow and hydraulic pumps turning in the absence of oil flow," says Betner. "This can result in hydraulic pump damage or sluggish operation at best.
Auxiliary heater units naturally help. But if they're not available, wide temperature range or multigrade hydraulic fluids that offer improved cold temperature fluidity can greatly improve cold temperature operation."
Keep hydraulic tanks full and dry
"Mobile hydraulic systems use big reservoirs," notes Ewing. "Moisture is the big culprit here."