Impress Your Mechanic: 6 Important Types of Car Fluid

Just like people, cars are full of fluids. Get a quick rundown of what each one does so you can feel smarter next time you visit the mechanic.

Do you know your engine fluids?

When I was young, no one told me (OK, fine, I ignored the fact) that cars need their oil and other fluids changed. Poor old Volvo ….

Now that I’m a super-mature grown-up (ahem), I know that regular oil changes are a must. But what about all those other mysterious fluids that make our car run? Do they need our attention too?

The answer is yes, they do. So for those of you who relate to young Jessica, here’s a simple breakdown of the types of car fluid that keep your vehicle running smoothly.

Motor oil … what does it actually do?

Changing your car’s oil is one of the most common car maintenance chores. But what has the stuff ever done for us?

Simply put, oil lubricates your engine. Because there are so many moving parts under your hood, oil reduces friction and keeps your engine from overheating. This lubrication also prevents rust by blocking oxygen from getting to the metal. And, as if it isn’t working hard enough already, oil traps dirt and other particles, leaving them behind in the oil filter (which is why it also pays to change your filter periodically).

So next time you’re due for an oil change, think about everything oil’s done for you lately and wipe that grimace off your face.

Transmission fluid: the other dipstick

There are 2 dipsticks under your hood: one to check your motor oil and one to check on that underrated worker bee, the transmission fluid. Transmission fluid performs many of the same functions as motor oil, like lubrication and cooling. As transmission fluid moves through an automatic transmission, it gets pressurized, which provides the hydraulic power needed to perform the transmission’s basic functions, like shifting gears.

For those of you with a stick shift, manual transmissions also require lubricant, but often use a different kind that has to be serviced from underneath the car (which means no dipstick).

Where does antifreeze stand on the whole freeze vs. no freeze debate?

Duh. Antifreeze wants nothing to do with freezing (or boiling for that matter). Adding antifreeze to the water in your radiator (a 50/50 mix is recommended) lowers the freezing temperature of the water, which helps prevent freezing in cold weather. After all, you want to keep your engine cool, not frigid.

Antifreeze can also protect that same water from boiling in the heat (hence its other name, coolant), but the name “antifreezeandboil” was a bit cumbersome.

Think you’ve seen it all? Well hold onto your hats because this overachiever even prevents corrosion and provides lubrication for the water pump.

Washer fluid is just water and colored soap, right?

Nope. Washer fluid combines several chemicals in order to perform services that soap and water alone couldn’t do. Standard washer fluid usually includes methanol, which can break down bug guts (yum!), as well as ethylene glycol, also common in antifreeze, to lower the freezing temperature of the washer fluid (unless you live in a warmer climate where antifreeze is less commonly added).

The good news is that more companies are now creating non-toxic washer fluids that still perform the same tasks as the other stuff. And some people even make their own washer fluid using household items. The Sierra Club recommends combining rubbing alcohol, liquid dish detergent, and water for a greener version.

What?! Even my brakes have fluid?

Hopefully. Because without brake fluid, you’re hosed. Like transmission fluid, brake fluid gets pressurized and provides the force that activates your brakes. When you push on the brake pedal, it engages a plunger in the master brake cylinder, which forces the brake fluid through a series of tubes and hoses and then into the braking unit of each wheel.

It sounds like a slow process, but for anyone who’s had to slam on the brakes to avoid a daredevil squirrel, we know that fluid moves fast!

Does power steering fluid truly give me power?

Similar to many of the other fluids in your car, power steering fluid provides lubrication for the steering gear and makes it easier to steer your car. When you turn the steering wheel, a small opening allows pressurized power steering fluid to move in and help you direct the front wheels. If that’s not power, I don’t know what is.

Now that you know your car fluid types, make sure to ask your mechanic to check all of them for a better picture of your car’s performance.

Class dismissed.

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6 Responses to “Impress Your Mechanic: 6 Important Types of Car Fluid”

  1. Avatar for Jessica Guerin
    A. R Tardiff
    March 23, 2013 #

    There's some 90W oil in the differential ball, in the rear axel of older cars, that pick up metal grindings from the spinning gears inside. Some models have a magnet on the inside part of the filler plug that catch these particles. The oil should be changed according to the maintenance schedule and the magnet (if you have one) cleaned of all particles.
    Convertibles (like my 1966 Lincoln) have ATF in the top workings.

  2. Avatar for Jessica Guerin
    T. Kohlmeyer
    March 26, 2013 #

    Those who have 4 wheel drive and all wheel drive vehicles will have other fluids to consider. There is often a transfer case that may have an independent cache of fluid and a separate differential for the front or rear wheels, depending on the basic configuration of the vehicle. Many of the newer crossover type vehicles will have the secondary differential driving the rear wheels. In any event, both of these differentials contain fluids and will require servicing from time to time. Consult you owners manual for the recommended intervals.

    I have an older, 1998 model Explorer that I converted all of the fluids (other than the windshield washer fluid) over to full synthetic. It still drives and runs like new at 160,000 miles. An added bonus – my mileage clicked up about 1 MPG on average. Not bad for a vehicle that originally only got about 18 MPG combined. I'll take that 5.6 percent improvement any day, not to mention the improved life it gives the components being lubricated due to the fluid's greater lubricity! Look into synthetics, they are well worth the cost when you look at the benefits!

  3. Avatar for Jessica Guerin
    Bill Tyree
    June 15, 2014 #

    Fluids deteriorate and collect moisture over time which leads to corrosion.
    At 50000 miles I took my wifes Lincoln Town Car in to the dealer and had every fluid system in it drained, flushed and refilled. Cost a bunch but the service manager told me that If I did this every 50 thousand miles the car would last forever. I knew that, but I modestly (I hope) only nodded.

  4. Avatar for Jessica Guerin
    September 17, 2014 #

    For manual transmissions, dont forget about the clutch fluid! (should be noted in the brake section as it is brake fluid)

  5. Avatar for Jessica Guerin
    Michael Green
    November 10, 2014 #

    Many motorists underestimate the importance of brake fluid and how often it should be checked!

  6. Avatar for Jessica Guerin
    Nash Rich
    June 6, 2016 #

    I didn't know that oil prevents rust from forming by blocking oxygen. That's really interesting, I would have never thought. I've never checked the transmission fluid before. I didn't even know there was a dipstick for it. Well, I guess I know one of my projects for the weekend!

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