Moisture is created by temperature changes. "Anytime air temperature changes from hot to cold, moisture can condense and convert to a liquid state," says Betner. "Checking for water contamination via oil analysis is one PM measure, along with avoiding shutdowns before the unit is up to operating temperature. Moisture in the oil can vaporize, but sufficient temperature and operating time is needed. Hydraulic systems may need removal of condensed water if an excessive amount is detected."
According to Ewing, the key is to keep the hydraulic reservoir full. He also recommends adding a desicant-type filter. "With a filter on there, that will remove the moisture as it goes in and out," he notes. "You really save yourself a lot of heartache."
A little preventive maintenance can also make life easier for your service technicians. "Before winter comes, it is sometimes a good idea to change the hydraulic filter," says Ewing. "During the summer, the filter may have plugged a little bit. It is not flowing quite like it should." This flow restriction can be compounded by cold fluid, which is harder to pump. "You start the equipment the first cold winter morning and suddenly you don't get the responsiveness out of the hydraulic system. It may be nothing more than a partially plugged filter, which is exaggerated now because of the really cold weather."
Change oil before storage
All of the oil suppliers interviewed recommend changing oil in equipment prior to storage. "During operation, the oil has picked up acids," says Ewing. "You burn the fuel, you have a little bit of moisture in there and you have sulfuric acid."
If acidic oil is left in seasonal equipment that is stored over the winter, internal engine damage in the form of pitting and corrosion may result. "It is best to change the oil," says Ewing. "Get fresh oil in it and run the machine for a while. Make sure that the fresh oil is circulated, then shut it off."
"By draining it before you store it, you have a fresh supply of additives that neutralize these acids," adds Arcy.
You also get rid of any contaminants in the oil. "It is good practice to change your oil to remove many of the contaminants the oil has suspended in it," says Gerig. "This helps reduce the chance of contaminants settling out."
During storage, avoid the temptation to start equipment every so often. "If you know you are going to let it run for an hour and get good and warmed up, that's one thing," says Ewing. "But too many guys will go out there, let it run for five minutes and shut it off. You get all of that moisture, you get the acids and you don't get enough good coating back on the cylinder walls. So it is typically a good idea to keep the oil fresh, get it parked and keep it as dry as possible."
Prior to storing equipment, Ewing advises, "Grease everything you can. A lot of times, moisture has set itself up in the ball joints and tie rod ends. A little shot of grease will push out a lot of the moisture that may be a problem in the spring."
When operating equipment in the winter months, extra grease can also prevent water contamination. "During winter usage, snow likes to find its way into places that rain never will," says Ewing. "Eventually that snow melts. So a little extra grease goes a long way."