6 Essential Car Fluids to Check Regularly

Imagine playing an entire basketball game without ever taking a drink. Or running a marathon after a steady diet of soda and beer—no water. Things wouldn’t turn out well for you!

Athletes’ bodies need water to perform their best. And, like an athlete, your car needs fluids to operate at peak performance.

Most people know that regular oil changes are necessary for good vehicle maintenance. But there are several different types of fluids that play crucial roles in your car’s ability to function.

If these fluids run dry or lose quality, you could end up with major damage to parts of the car, rendering it unsafe to drive or unable to start. So here are the 6 crucial car fluids that you should check regularly as part of your vehicle maintenance routine.

6 Essential Car Fluids

Engine Oil

Oil is massively important for your car engine’s ability to run. When your car’s oil isn’t changed out as frequently as it should be, the engine will lock up—your car won’t start.

You could end up with a $5,000 bill just to get your car running again if you let the engine run dry! That’s why it’s so important to follow your vehicle’s recommended oil change interval.

When to Check Your Oil: It’s best to check your motor oil when the car is off. For best results, go for a short drive and then check the oil after the car has cooled down for 5-10 minutes.

How to Check Your Oil: Pop the hood and find the oil dipstick (typically toward the front or rear of the engine). Pull it out and then wipe it off with a cloth or towel. Reinsert it and then pull it out and check the oil level.

There should be marks on the dipstick indicating the acceptable oil level range. Take note of the oil level and quality: is it gritty and dark? Or smooth and transparent?

We recommend checking your oil monthly, especially if you suspect that your vehicle may be burning oil.

How Often to Change Your Oil: Most modern vehicles can go 5,000-10,000 miles (or 6 months) between oil changes. Check your owner’s manual for the best service interval for your car.

Read: How Long Can You Go Without an Oil Change?

Transmission Fluid

If you drive an automatic car, the fluid in your transmission is what keeps your gears shifting seamlessly. This important fluid isn’t checked as part of the annual Virginia state inspection, but it does need to be replaced at regular intervals.

Like any other car fluid, transmission fluid degrades over time. Good transmission fluid is usually red, but it darkens to deeper shades of red, brown or even black as it ages. If your transmission fluid is a dark brown or black color or if it is gritty, then it needs to be replaced.

When to Check Transmission Fluid: Check the transmission fluid while the car is running (make sure the vehicle is in park first).

How to Check Transmission Fluid: For many cars, checking the transmission fluid is very similar to checking the oil. There should be another dipstick in the engine for the transmission fluid. Pull it out, wipe it off, and then reinsert it. Pull it out again to check the transmission fluid level and quality.

For cars without a dipstick, you’ll need to take your vehicle to a professional to check the fluid.

How Often to Change Transmission Fluid: You should get a transmission fluid flush every 30,000–60,000 miles or every 3 years. Check the owner’s manual for your vehicle manufacturer’s recommendation.

Differential Fluid

Differential fluid is probably the most neglected car fluid. And this may be because many car owners don’t know what a differential is! Simply put, the differential works with your transmission to transfer power from the engine to the axles.

Most vehicles have a front differential, and 4-wheel-drive (4WD) vehicles and rear-wheel-drive (RWD) have a front differential and a rear differential. The differential fluid prevents overheating and metal-on-metal contact, allowing the differential to run smoothly.

Because of the location and design of the differential, the differential fluid cannot be checked before it is changed.

How Often to Change Differential Fluid: Differential fluid needs to be replaced every 30,000 to 60,000 miles, depending on the car manufacturer’s recommendation. While you could try to do it yourself, it’ll be a lot easier, cleaner and faster if you leave it to the pros.

Note: 4WD vehicles and some all-wheel-drive (AWD) vehicles also have a transfer case, which helps control the power being sent to the differentials. If your vehicle has a transfer case, check the owner’s manual for how often to change the transfer case fluid.

Coolant

Engines create a lot of heat while running. Coolant (also called antifreeze or radiator fluid) circulates through your engine to keep it from overheating. It also lubricates water pump bearings and inhibits corrosion in the engine.

Over time, rust and contaminants build up in the engine’s cooling system. As a result, the coolant is less effective, leading to premature wear of engine parts or even engine failure. And if your coolant level is too low, you risk overheating the engine.

When to Check Coolant: Never open the radiator cap while the vehicle is hot or running! The radiator is pressurized, so wait until the vehicle has cooled down completely to check the coolant level.

How to Check Coolant: Some vehicles have a coolant overflow reservoir near the radiator where you can check the coolant level. If not, remove the radiator cap and look inside to check the coolant level.

The quality of the coolant can be tested by inserting test strips that measure the coolant’s PH (acidity) and glycol level (antifreeze).

How Often to Change Coolant: Some car manuals suggest changing coolant every 30,000 miles, while others say your car can go more than 100,000 miles between coolant flushes. Check your owner’s manual to be sure.

Brake Fluid

Brake fluid is checked during the annual Virginia state inspection because of how important it is to safe driving. Low brake fluid or poor fluid quality significantly impacts brake performance.

Your car’s brake fluid is part of a powerful braking system. It multiplies the pressure you put on your brake pedal into enough force to stop the car.

If your brake fluid is leaking or contaminated, it will take you much longer to stop and potentially damage your braking system.

When to Check Brake Fluid: Your brake fluid should be checked each year as part of your Virginia safety inspection. If you notice any problems during the year, check the brake fluid when your car is off and the engine is cold.

How to Check Brake Fluid: Find the brake fluid reservoir in your engine bay. (If you’re not sure where to find it, check the owner’s manual.) There should be marks on the side indicating the required minimum and maximum fluid levels.

To find more complex issues with the brake fluid, like air or water in the brake lines, you’ll need the help of a qualified technician.

How Often to Change Brake Fluid: Brake fluid should be changed out every 2 years or 45,000 miles. For your vehicle’s specific recommendation, —you guessed it—check the owner’s manual.

Read: How Do I Know When I Need New Brakes?

Power Steering Fluid

Power steering is standard in most cars today—many drivers on the road haven’t experienced driving a car without it! But power steering won’t work without adequate lubrication.

Power steering fluid is pressurized by a hydraulic pump to make turning easier. It also serves to lubricate the components of the steering system.

Any leaks or contaminants have the potential to damage the steering system, so it’s important to check the power steering fluid regularly for any issues.

When to Check Power Steering Fluid: Check the power steering fluid when the engine is cold (the vehicle is off).

How to Check Power Steering Fluid: Look around in your engine bay to find the power steering reservoir (usually on the passenger side). There should be a mark on the side indicating the required minimum level.

How Often to Change Power Steering Fluid: On average, it needs to be changed out every 2 years, but check your owner’s manual for the manufacturer’s recommendation. Every make and model is different.

Fluid Tips & Warnings

• Always park on level ground to get accurate fluid level measurements.
• Always check the owner’s manual first!
• If you need to fill up a fluid reservoir, be careful to only use fluids that meet the specifications outlined by the manufacturer.
• Before opening a reservoir cap or pulling out a dipstick, use a clean rag to clean off the area around it. Any dirt or contaminants that get into the system could cause future damage.
• Don’t overfill—too much can be just as harmful as too little.
• Don’t forget about the windshield washer fluid! Keep it topped up year-round and switch to an antifreeze washer fluid in winter.
• If you see a small puddle of water underneath your car, there’s no need to panic. When you run your air conditioning system, condensation built up in the system drains underneath your car. If you see drips or puddles that are red, brown, green or any other color, it’s time to make a trip to Virginia Tire & Auto for a vehicle check-up.

Vehicles Run on Fluids

Checking your vehicle’s fluids every few months is a key part of vehicle maintenance. At Virginia Tire & Auto, we include this service for free as part of our 25-Point Vehicle Inspection! You can rest assured that your car fluids are topped off after every oil change or other service.