This fall, Construction Equipment has been talking with industry experts about keeping machines running when temperatures turn chilly. Our ongoing winter maintenance Q&A series has already featured advice from Volvo Construction Equipment, CITGO, and Takeuchi, covering fluid selection, frozen tracks, cold starts, proper warmup procedures, you know, basically overall cold-weather preparation, operation, and maintenance.

For this latest installment, we’re focusing on the fluids that keep construction equipment running. We spoke with Max Cundiff, industrial sector manager at Chevron, about choosing the right engine oils, keeping grease flowing in freezing temperatures, and protecting hydraulic systems from cold-weather damage. Cundiff covers an awful lot. So, without further ado, here’s what fleet managers and operators should know before the deep freeze arrives.

CE: First off, Max, thanks so much for taking the time to talk today. We are big fans of the Chevron brand, so we’re excited to hear your insights into cold-weather maintenance. To start us off, when should contractors begin thinking about winterizing their fleets? 

Cundiff: Realistically, there's no single start date that works for every fleet. Geography drives the timeline more than anything else. Most contractors begin planning for winter conditions as they move into the third quarter, but crews in northern climates should build in extra lead time, since a cold snap can arrive earlier than expected.

The real principle is to treat winterizing as a preemptive strike rather than a reaction. Contractors who wait until temperatures actually drop often find themselves troubleshooting issues that were completely invisible over the summer, from thickened fluids to grease that won't flow. Getting ahead of that curve, checking fluid specs, inspecting fittings, and confirming the right products are in the tank before the cold sets in, saves far more downtime than scrambling once equipment starts struggling in the field.

How does cold weather affect engine oil performance? Should contractors switch to different oil viscosities for winter operation?

Viscosity is one of the single most important specifications for any oil, and cold weather puts that spec to the test. Oil naturally thickens as temperatures drop, and the goal is to create a lubricant that would hold a flat viscosity no matter the conditions. The industry term for how quickly a fluid's viscosity shifts with temperature is viscosity index or VI, and it's worth understanding because it drives real decisions about what goes into a machine each season.

Engine oil is typically changed often enough that seasonal viscosity adjustments are practical. Fluids like hydraulics, transmissions, and final drives are typically swapped far less frequently, which is where synthetics earn their keep. Synthetic formulations generally take longer to thicken in the cold and hold up better in the heat, giving contractors a wider operating range without needing to change fluids as the seasons shift. The construction industry is moving in that direction, following a path the automotive world has already largely completed.

The moment that matters most is cold start. Once a machine is running and its components are generating heat, fluid tends to behave well regardless of ambient temperature. The risk is concentrated in that first startup, so a good rule of thumb is keeping a fluid's pour point 20 to 30 degrees below the coldest temperature it will face, and checking OEM startup viscosity specs to avoid cavitation before the machine has a chance to warm up. Reviewing product and technical data sheets before the season changes is a simple step that pays off every time temperatures swing.

How does cold weather affect grease performance in pins, bushings, bearings, and swing systems? Are there specific grease formulations better suited for snow, freezing rain, or prolonged cold?

Most contractors won't notice a difference in how grease performs until they try to pump it. In extreme cold, grease can stiffen to the point that it stops moving altogether. Short of that extreme, the variable that matters most is NLGI grade, the industry scale that reflects the stiffness of the grease and, in turn, how easily it pumps. Many construction fleets turn to a Grade 2 in summer and shift to a Grade 1 in winter for better flow, and central lubrication systems with long capillary runs may need to go even further, down to a 0, 00, or even 000.

Grease composition matters too. Calcium-based greases are gaining ground in construction because they may pump better than lithium at the same NLGI grade, hold up better against water, and resist washout whether that water comes from a pressure wash or just normal exposure on the jobsite. That water resistance is a meaningful advantage in the wet, snowy, or icy conditions winter often brings. Calcium and lithium greases are also compatible with each other, so switching between them doesn't carry the risk of incompatibility that can come with mixing other grease types.

One story from the field makes the point well. A mine in Alaska insisted it needed a Grade 1 for winter, but the calcium-based grease wasn't yet available in that grade. The customer kept calling, asking when the Grade 1 would be available and the pressure was on internally to get it up there fast. Then the calls stopped. The team feared they'd lost the account, until they realized what had actually happened: once temperatures dropped, the calcium Grade 2 pumped so well in the cold that the customer never needed the Grade 1 in the first place.

Which machine components benefit most from fresh lubrication before winter? How can contractors avoid over-greasing or under-greasing during cold weather?

Every component benefits from clean, fresh lubrication heading into winter, but contamination control is what makes the difference. Dirt, silica, and soot, a natural byproduct of diesel engines,  can clump together into larger, abrasive particles that act like sandpaper inside a system. Dispersants help keep those particles small, and filtering helps remove them, but neither eliminates the problem entirely. That's why ISO cleanliness levels matter: Caterpillar targets ISO 16/13, and most properly maintained lubricants exceed that standard, but it requires consistent filtering and attention to stay there.

Over-greasing is a less obvious risk than under-greasing, but it's just as damaging. A common rule of thumb in the field is to keep greasing until the seal pops, but that approach can backfire. Seals aren't fixed in place, and once one pops out of position, it may not seal correctly again, letting contamination into the component. Bearings almost always have seals, while bushings often don't, so the risk profile differs by component.

One of the most reliable methods is ultrasonics. A technician listens as grease is pumped in, and the sound of the bearing changes at a specific point, dropping and then rising again once the bearing is full. That's the signal to stop. Logging how many pumps or squirts it takes to reach that point, and building it into a PM chart, turns a one-time observation into a repeatable standard for the whole fleet.

How does cold weather affect hydraulic oil and machine performance? Are there hydraulic fluids designed specifically for cold climates?

Hydraulic systems are especially sensitive to viscosity in cold weather. If the wrong fluid is paired with a severe cold start, the result can be cavitation or a breakdown in boundary lubrication, both of which put real wear on the equipment. The industry's answer has increasingly been multi-viscosity and high-VI fluids that perform well across a wide temperature range rather than requiring a seasonal swap.

Viscosity index measures how much a fluid's viscosity shifts with temperature, and base oil plays a major role in that performance. A conventional hydraulic base oil typically sits around a VI of 100. Adding VI improvers can push that closer to 150, and full synthetics can reach up to 200, which represents the strongest cold-weather performance available. Many fleets, particularly in colder regions, have shifted to a premium high-VI fluid used year-round specifically to avoid the hassle and risk of switching products every season.

Water contamination is another cold-weather hazard worth watching closely. Water is heavier than hydraulic fluid, so it settles to the bottom of a system, and if enough accumulates and the temperature drops far enough, it can freeze into a solid obstruction. It's a reminder that cold-weather hydraulic performance isn't just about the fluid's viscosity; it's also about keeping the system clean and dry.

What’s the proper way to warm up hydraulic systems before putting a machine under load?

In extremely cold regions, some operators choose to keep equipment running continuously, never shutting it down. Keeping a hydraulic system cycling allows it to generate and retain its own heat, which keeps fluid moving freely and ready to perform when the machine needs to work.

There isn't a single formula that applies to every machine or every climate, so contractors should lean on OEM guidance and their fluid's cold-temperature properties as the starting point. What matters most is giving the system time and consistent operation to reach a stable temperature before it's put under real load, rather than assuming a quick startup is enough.

If a contractor only has one day to prepare an entire fleet for winter, what are the highest-priority maintenance tasks?

Honestly, one day isn't enough time to properly winterize an entire fleet, but if forced to prioritize one item, ensuring grease is reaching bearings and bushings would be near the top of the list. If grease stops moving once temperatures drop, the components downstream don't care how well the rest of the fleet was prepped. They wear or fail anyway.

With whatever time is left, put it toward two things: figuring out which products are already in the fleet and where they'll fall short against the coldest temperatures expected, then making sure the right replacement inventory is actually on hand. A contractor who nails grease flow and closes those inventory gaps in a single day has done more real winter prep than one who tried to touch every machine on a longer list but rushed through it.

Which inexpensive winter maintenance steps deliver the biggest return on investment? Which of your products or technologies have made the biggest difference in winter uptime over the last five years?

Coolant is consistently the most overlooked, highest-ROI item on the winter maintenance list. Most cooling systems run on a roughly 50/50 mix of water and ethylene or propylene glycol, and cooling problems are usually your number one maintenance issue across fleets in general, not just in winter. A simple refractometer check at every PM interval tells a technician the freeze point and glycol concentration of the coolant, which is inexpensive insurance against a much costlier failure.

One detail that catches contractors off guard: water evaporates exponentially faster than glycol. Small leaks or evaporation over time can push glycol concentration higher than intended, which sounds like it should improve freeze protection but can actually cause overheating, since glycol concentration above roughly 60 percent starts to work against freeze protection rather than for it.

The seasonal switch is also a natural checkpoint to pull a fluid sample from the tank and test for contamination, viscosity, and water content, confirming that what's in the tank matches what's expected. A quick QA pass on pump pressures and fittings when switching products rounds out a low-cost, high-value routine that catches small problems before they become downtime.

Looking ahead, what innovations will make cold-weather operation easier for construction fleets?

Equipment design and lubrication technology are in a constant back-and-forth, and that dynamic isn't going away. As machines run hotter and oil sump sizes shrink to meet tighter engineering tolerances, the pressure moves toward synthetics and lower-viscosity fluids that can keep pace with those changes. New diesel specifications are introducing 0W-20 into heavy-duty engine oil, which is a clear example of that shift already underway, since a lighter oil flows better at cold start without sacrificing protection once the machine is running.

Lubricant innovation will continue to track equipment engineering closely, with antiwear, extreme pressure, and antifoam additive packages evolving alongside tighter machined tolerances. But the most important takeaway isn't really about a future breakthrough. As one of our formulation experts, with 42 years in the industry, put it: If the right fluid is in the right place and it's clean and dry, he's never once been able to blame a failure on the lubricant. That principle will outlast any single innovation, and it's the foundation contractors should build their winter prep around regardless of what comes next.