You know that feeling when your car is running just right?

The engine purrs, acceleration is effortless, the ride feels smooth, and there’s no warning light in sight. That kind of peace-of-mind driving doesn’t happen by accident. It’s the result of regular maintenance. And at the top of that list? Checking your car’s fluids.

Fluids are your car’s lifeblood. They cool, lubricate, protect, and power essential systems. If even one of them is low or degraded, it can throw your car’s performance off track. Or worse, lead to expensive repairs.

We see it every day at our Denver shop. A quick fluid check could’ve prevented a major issue. That’s why we’re diving into the six most important fluids to keep tabs on—and how to check them.

Engine Oil: The One Everyone Knows (And Still Sometimes Forgets)

Let’s start with the obvious one—engine oil. This is the fluid you hear about most, and for good reason. Your car’s engine oil lubricates moving parts, reduces friction, prevents overheating, and captures dirt and particles to keep things running clean.

You should be checking your oil level regularly, at least once a month, and before you head out on long trips. Look at the oil level, color, and consistency. 

If the oil is dark and dirty, it’s time for a change. If it’s low, top it off with the recommended grade listed in your owner’s manual. Milky oil could mean coolant is leaking into the engine (yep, that’s a red flag).

Changing your oil should be on your calendar – every 3,000 to 10,000 miles, depending on what your car’s manufacturer recommends. But we still recommend being proactive. Don’t just wait for the oil change reminder sticker. Denver’s stop-and-go traffic and elevation can put extra strain on your engine. When in doubt, check it.

Coolant: Your Engine’s Temperature Regulator

Coolant (or antifreeze) is responsible for absorbing heat from your engine and releasing it through the radiator. Without it, your engine would overheat in a hurry, especially during Colorado’s high-altitude summers.

Check your coolant level in the overflow tank, and monitor the fluid color and cleanliness. We suggest checking it every few weeks—more often in hot weather.

The fluid should be bright green, orange, or pink, depending on the type. If it’s rusty, cloudy, or low, it needs attention.

Any sign of coolant leaking under your car or a sweet smell from the engine? Get it checked right away.

Reminder: Never open the radiator cap when the engine is hot. Always check coolant levels when the car is cool.

Brake Fluid: Small Reservoir, Big Responsibility

Your brakes rely on hydraulic pressure to function. That pressure comes from—you guessed it—brake fluid. Low or dirty brake fluid can reduce your stopping power and lead to that dreaded soft or spongy brake pedal feel. Brake fluid is hygroscopic; it absorbs moisture from the air. That means it naturally degrades over time, even if you don’t drive much.

That’s why it’s important to check brake fluid level in the reservoir, and monitor the color and clarity. Checking it every few months is fine, or during every oil change.

Look for the fluid to be clear to light yellow. If it’s dark or has particles in it, it’s time for a flush. If the level is low, it might indicate a leak or worn brake pads (which draw more fluid as they wear).

Transmission Fluid: Smooth Shifting Starts Here

Your automatic transmission is one of the most complex (and expensive) systems in your car. Transmission fluid keeps it cool, lubricated, and functioning smoothly. But like any fluid, it wears out over time.

Check the transmission fluid level and condition (use the dipstick if your car has one). Check monthly if your vehicle allows. Some newer vehicles have sealed systems that require a shop check.

You should look for fluid that should be red or pink and smell slightly sweet. If it’s brown, dark, or smells burnt, it needs to be changed. Low fluid could indicate a leak, and that’s not something to ignore.

Note: Transmission fluid doesn’t need to be changed as often as engine oil, but when it does, trust us—it makes a big difference.

Power Steering Fluid: Easy Turns, No Squeaks

Ever had your steering wheel feel stiff or jerky? That could be a sign your power steering fluid is low. This fluid makes it easy to turn your wheel with minimal effort, especially important when navigating tight Denver parking lots or winding mountain roads.

You should check the power steering fluid level and appearance. Check it every month, or during regular oil changes.

Look for fluid to be reddish or amber. If it’s dark or smells burnt, it’s time for a flush. Whining noises or hard steering can be signs of low fluid or a failing pump.

Windshield Washer Fluid: Visibility Is Safety

Last but not least—washer fluid. Sure, it won’t break your car if you run out, but a clean windshield is critical to safe driving. Dust, road grime, and bug splatter can build up fast, especially in Colorado’s ever-changing weather.

You’ll want to check fluid level in the reservoir, spray nozzles, and wiper function. We suggest checking anytime you fill up with gas or before a road trip.

Keep the reservoir topped off with proper washer fluid, not just water, especially in winter. If no fluid comes out when you hit the switch, the lines could be clogged or frozen.

Bonus Tip: Know What’s Right for Your Vehicle

Always consult your owner’s manual for the correct fluid types and service intervals. Using the wrong fluid—even if it’s close—can cause more harm than good. And if you’re unsure? That’s what we’re here for.

At Denver Express Care, we’ve helped thousands of drivers get to know their cars better. And keep them running at their best. Whether you just want a quick fluid check or a full inspection before a road trip, we’re your neighborhood shop for honest, reliable service.

If any of these fluids look low, dirty, or just plain off—and you’re not sure what to do—don’t take a guess. A simple fluid issue can spiral into engine damage, brake failure, or major transmission problems if left unchecked.

We make it easy to stay on top of your car’s maintenance without breaking the bank. Just swing by, and we’ll take a look. Our certified technicians can quickly check and top off your fluids, make maintenance recommendations, and catch problems early. Before they turn into big repair bills.

Drop by Denver Express Care or schedule an appointment today. We’ll help you keep your vehicle in peak condition. Fluid by fluid, mile by mile.