Winter in Vermont can be brutal on machinery. When the temperatures drop to -10° or lower, it’s not always the heavy snow or ice that threatens your backup power—it’s often something much simpler: the oil.

Yes, the very substance that keeps your engine running smoothly can be the reason it fails when you need it most.

The Science of “Cold Soaking”

Generators have a unique challenge compared to your car. Your car is driven daily, keeping the oil circulating and the battery charged. A standby generator, however, sits perfectly still for weeks at a time, often in freezing temperatures.

This process is called “cold soaking.”

When oil sits in sub-zero temperatures, it thickens (increases in viscosity). If your generator is filled with standard conventional oil, that oil can turn into a substance resembling molasses.

Why Viscosity Matters

When the power goes out, your generator is expected to go from a dead stop to full RPMs in a matter of seconds.

If the oil is too thick:

Slow Cranking: The engine struggles to turn over, draining the battery before the unit can start.
Low Oil Pressure Faults: Even if it starts, the oil pump can’t move the thick sludge fast enough. The sensors detect a lack of pressure and immediately shut the engine down to save it, leaving you in the dark.
Engine Damage: In the worst-case scenario, the engine runs without proper lubrication for those critical first seconds, leading to metal-on-metal wear or a seized piston.

The Solution: Synthetic & Winter-Rated Oil

Not all oils are created equal. For Vermont winters, 5W-30 Full Synthetic is the gold standard for most air-cooled generators.

Unlike conventional oil, synthetic oil maintains its fluidity even in extreme cold. It allows the engine to crank faster and lubricates critical components instantly upon startup.

Brook Field Service Recommendation: Check your owner’s manual. Many older units may still have 10W-30 or SAE 30 oil in them from a summer service, which is not rated for our winter temperatures.

Pro Tips for Winter Reliability

Even the best oil won’t save a neglected machine. Here is your checklist to ensure your lights stay on this February:

Check the Dipstick Weekly: If the oil looks gritty, black, or thick, it needs to be changed before the storm.
Install a Cold Weather Kit: For standby units, we highly recommend installing a battery warmer and an oil warmer. These keep the engine block at a moderate temperature, ensuring a summer-like start even in the dead of winter.
Exercise the Unit: Make sure your weekly exercise cycle is set. This keeps the internal components lubricated and “wakes up” the battery.

Don’t Let the Cold Win

Don’t let a $20 quart of oil cost you a $10,000 engine. Taking simple steps now—choosing the right winter-grade oil and performing regular maintenance—can keep your backup power reliable all season long.

Need help winterizing your generator? At Brook Field Service, we go where the GPS won’t to keep Vermonters powered.