Why Coolant Matters in the Winter (And What Every Marion, IL, Driver Should Know)

When most drivers hear the word coolant, they think about summer heat and overheating engines. But here’s something that surprises a lot of people:

👉 Coolant is just as important—if not more important—during winter.

In cold weather, your vehicle’s cooling system works hard to protect your engine, maintain proper temperatures, and even keep you warm inside the cabin. Neglecting coolant in winter can lead to breakdowns, expensive repairs, or even permanent engine damage.

Let’s break down what coolant does in winter, how it protects your engine, and how PMR Automotive in Marion, IL can help keep your vehicle safe when temperatures drop.

What Is Coolant (Antifreeze), Really?

Coolant—often called antifreeze—is a specially formulated fluid that circulates through your engine and radiator. It’s designed to:

• Prevent freezing in cold temperatures

• Prevent overheating when the engine warms up

• Protect metal components from corrosion

• Lubricate the water pump and seals

Most vehicles use a 50/50 mix of antifreeze and water, which provides freeze protection well below zero and stable operation year-round.

If that mixture is wrong—or the coolant is old or contaminated—winter can expose problems fast.

Why Coolant Is Critical During Winter

1. Prevents Coolant From Freezing

Water alone freezes at 32°F. When it freezes, it expands—and that expansion can crack engine blocks, radiators, heater cores, and hoses.

Proper antifreeze lowers the freezing point (often to -30°F or lower), and keeps coolant flowing even in extreme cold

Without the right coolant mixture, one cold snap can cause catastrophic engine damage.

2. Protects Against Cold-Start Engine Damage

Cold starts are one of the hardest moments for an engine. Oil is thicker, metal parts contract, and internal clearances change.

Coolant helps by regulating temperature as the engine warms up, preventing uneven expansion of engine components, and reducing stress on gaskets and seals

In winter, your cooling system doesn’t “rest”—it actively manages temperature stability.

3. Keeps Your Heater Working Properly

Your vehicle’s cabin heat comes from the heater core, which uses hot coolant heated by your engine to warm the air inside your car.

If coolant is low, contaminated, sludged, or air-locked, you may experience:

• Little or no heat

• Fogging windows

• Sweet smells inside the cabin

• Coolant leaks under the dash

A properly serviced cooling system means a more reliable heat and defrosting, which is essential for winter safety.

4. Prevents Internal Corrosion During Cold Months

Coolant doesn’t just control temperature—it contains additives that prevent rust and corrosion inside the system, including the radiator, heater core, water pump, and engine passages.

Over time, those additives break down. Old coolant becomes acidic and corrosive, especially when exposed to winter temperature swings. This can lead to issues such as:

• Clogged radiators

• Heater core failure

• Water pump leaks

• Overheating later in the year

A coolant flush at the proper interval helps prevent these expensive repairs.

Common Winter Coolant Problems We See in the Shop

At PMR Automotive in Marion, IL, winter is when cooling system issues really show themselves. Some of the most common problems include:

Low Coolant Levels

Cold temperatures can reveal slow leaks from hoses, clamps, radiator seams, or water pumps, often time hidden by warmer temperatures.

Cracked or Brittle Hoses

Rubber hoses become stiff in cold weather and may crack or split under pressure.

Weak Coolant Mixture

Too much water in the system = freeze risk. Too much antifreeze = reduced heat transfer.

Stuck Thermostats

Thermostats can get stuck in many positions, but the two most common are open or shut.

A thermostat stuck open can cause:

• Poor heat

• Reduced fuel efficiency

• Engine running too cool

A thermostat stuck closed can cause:

• Overheating

• Pressure buildup

• Hose failure

  
  

Signs Your Coolant System Needs Attention This Winter

If you notice any of the following, it’s time to have your vehicle checked by a mechanic:

• Temperature gauge reading colder or hotter than normal

• Heater not blowing warm air

• Sweet smell inside or outside the vehicle

• Visible coolant leaks or puddles

• Low coolant warning light

• Frequent need to “top off” coolant

Ignoring these signs can lead to no heat, breakdowns, or engine damage—often at the worst possible time.

Does Coolant Go Bad Over Time? Yes.

Many drivers don’t realize coolant is a maintenance item, not a lifetime fluid. Over time, corrosion inhibitors wear out, coolant becomes acidic, contaminants build up, and freeze protection weakens

We typically recommend coolant replacement every 5 years or 60K miles, depending on the type of coolant and vehicle.

At PMR Automotive, we:

• Test freeze protection

• Inspect coolant condition

• Check for leaks and pressure issues

• Recommend service based on your vehicle—not guesswork

  
  

Why Winter Is the Best Time to Check Your Cooling System

Winter exposes weak spots quickly. A system that “worked fine” in fall may struggle once temperatures drop.

A winter cooling system inspection can:

• Prevent no-heat situations

• Catch leaks early

• Protect against freezing damage

• Avoid surprise breakdowns

• Save money long-term

It’s a small investment compared to the cost of engine or heater core repairs.

Trust PMR Automotive for Cooling System Service in Marion, IL

Whether your vehicle needs a coolant flush, leak inspection, cooling system part replacement, or heater performance diagnosis, The team at PMR Automotive has you covered.

Your cooling system works year-round, and winter is when it’s tested the most. Proper coolant protects your engine, keeps you warm, and helps your vehicle start and run reliably—even in freezing temperatures.

If you’re unsure about your coolant condition, don’t guess. Contact us right away to set up an appointment for your vehicle!

PMR Automotive

📍 900 E DeYoung St, Marion, IL

🔧 618-998-9010

Let us help keep your car safe, warm, and reliable all winter long.