State of Flow

As with humans, there are many fluids that keep our cars going. It’s important to know what these fluids do and how they work in order to maintain the dependability of our vehicles. Your ability to connect your car’s problems, strange sounds, and erratic functions with the fluid that is part of getting the job done may help you diagnose a problem before it turns into a giant mechanic bill. The key lies in your ability to check each fluid and spot issues.

Before we get started, you may want to grab your owner’s manual and keep it handy. In it, you should be able to find a chart with each fluid, the type that is recommended for your engine, and even how often you should be checking and replacing them. Park your car on a level surface—as level as you can find in these streets—in order to get the most accurate reading for any of these fluids.

Engine Oil

We’ve talked about changing your oil before, and we’ve also talked about checking for water in your oil, but we didn’t quite go over how to check the quality and health of the oil currently in your engine as part of regular maintenance. Engine oil is often referred to as the lifeblood of your vehicle. When it is brand new, it is amber or light brown in color, but may look almost clear as a thin coat on your dipstick.

Since energy cannot be created or destroyed, the potential energy we unleash when burning gasoline inside the engine can either go towards making your car move, or towards creating heat or noise. Think about rubbing two pieces of raw metal together—there will be a loud, unpleasant noise and the metal will get hot from the friction. Now try putting a little bit of engine oil between those two pieces of metal; they glide over each other effortlessly and silently. Of course, there will always be heat and noise when running a combustion engine, but if there is an excess of either of those two it’s a big sign your car is not running as efficiently as it could be.

The thickness of the oil is referred to as the viscosity or the weight of the oil. Most cars on the road these days will require a multi-grade oil. Your oil packaging should say something like: SAE 10W-30. SAE stands for Society of Automotive Engineers, the association that grades the oil. The first number, “10W,” tells us the winter or cold temperature performance of that oil. In cold temperatures all liquids move slower, or are thicc, as the kids say. The higher the rating number, the thicker the oil. We want a thin oil when the engine is cold so the engine isn’t fighting against the thickness of the oil when starting, causing extra strain and potential damage. This is why that first number followed by the “W” will always be lower than the second one. This second number, “30,” tells us the weight of the oil when the engine is at operating temperature, about 212 degrees Fahrenheit (Cue your best Paris Hilton impression). You don’t want your oil to be too thin at operating temperatures because you want it to properly lubricate every part while your engine is, well, operating.

You may also be curious about the difference between conventional, synthetic, and synthetic blend oils. Conventional oil is created by refining crude oil—yes, like the stuff constantly being spilled into the Gulf. Conventional oil is generally cheaper, but it does not last as long and is not recommended in extreme conditions. Synthetic oil consists of polymers created in a lab and contains fewer impurities, making it last longer and perform better in extreme conditions, although it is pricier. The synthetic blend oil is a blend of the two, the Goldilocks of the bunch, giving you an in-between price and an in-between performance. And yes, I would consider New Orleans to be extreme conditions.

In addition to lubricating the engine, the oil also absorbs debris from combustion. Your oil will progressively get darker and grimier the more you drive your vehicle because it is capturing the soot from burning fuel. There comes a point where your oil’s lubrication properties are being thwarted by how dirty it is, which is about every 3,000 miles, or every six months. If your car is particularly old or is running poorly you may want to keep an eye on the quality of your oil by checking it more regularly.

Check the oil level on your dipstick. Before adding new oil, take note of how dark the color is. Dark oil is not necessarily bad, unless you’ve just had an oil change. If the oil is dark and also feels gritty or sandy between your fingers, that is definitely bad and you should do an oil change ASAP. When you are changing the oil keep an eye out for any metallic pieces, small or large. This means the metal parts in your engine are being ground down into magical metallic glitter. And although it looks real purdy, it’s not a good sign. If you see anything like that I would recommend taking down your oil pan and seeing if there is any metallic looking sludge or bigger metal pieces on the bottom. If there is, clean it out as best you can, refill your engine with fresh oil, and give your best friend, the mechanic, a call.

Automatic Transmission Fluid

No matter how much you may want to have a manual transmission vehicle, chances are you probably don’t. The fluid that keeps your automatic transmission functioning is unimaginatively called automatic transmission fluid, or ATF. It is usually colored red (sometimes even green) to differentiate it from your engine oil.

There are certain ATFs which are specific to certain manufacturers, some which are more general, and some specifically formulated for older and classic cars. If you have a hybrid you likely have a continuously variable transmission (or CTV), which will require its own special fluid as well. Refer to your owner’s manual if you are confused about which kind you need.

It performs some of the functions as engine oil, such as lubrication, but it also needs to work as a hydraulic medium. A running engine creates pressure in your transmission; the differences in the pressure while you are driving is what automates the gear changes. The ATF acts like a messenger between the engine and the gears in your transmission. This also means that when you are checking the level of your automatic transmission fluid, you will need to do it while your car is running.

Since the ATF isn’t experiencing any combustion (unless something is very, very wrong) it doesn’t get as dirty as fast as your engine oil. If the fluid does look very dark and smells burnt it might be time to start saving some money for your emergency transmission replacement fund. Also be on the lookout for that same magical metallic glitter or any metallic shards. If you are experiencing any hard or lazy gear shifting or any clunking, this may be a sign you are low on ATF or you are due for some new fluid. You will only need a complete transmission flush every 50,000 miles, but you may elect to do a fluid change (which replaces 50-60% of the fluid) more often to keep your transmission in top shape.

Brake Fluid

Just like ATF, brake fluid serves as a hydraulic medium except it powers your brakes. It carries pressure from the pedal which is amplified and distributed to all four calipers, which apply pressure to the rotors which are attached to your wheels. This pressure stops your wheels from turning, causing you to stop. Brake fluid is usually clear with a light yellow hint. It also smells kind of fishy and feels very slippery, kind of like bleach. Definitely avoid touching it with your bare hands or spilling it on any finished paint, as it is extremely corrosive.

Brake fluid should be replaced every 30,000 miles or every two years. Obviously, if you are having any kind of issues with your brakes, the first thing you should do is check that brake fluid level and color. Old brake fluid will have a brown to dark brown appearance; the darker it is the likelier you are due for a change.


Since we’ve already discussed how to do a coolant flush, I assume everyone in New Orleans is now a pro at recognizing their coolant. Coolant, or antifreeze as it’s usually known to those in places where it actually freezes, is neon green in color but as it gets older and gunkier it turns to a darker and darker rusty brown. As the name implies, it also helps stop your engine from freezing and cracking if you are ever somewhere that cold for long enough. Coolant only needs to be replaced about every 30,000 miles.

Coolant also smells very sweet, which can help you identify it. Because of this it can be very dangerous to wild animals and pets, as they will happily lap it up if they find it unsupervised. Please take great care not to leave any puddles while you are working with it. If you do happen to spill some coolant on the ground, wash it off with water as soon as possible. If you find yourself smelling that sweet syrupy smell coming from your tailpipe, shut off your car immediately, check your oil, and call your mechanic. Coolant should never enter the oil or combustion chambers of your engine, and if you’re smelling it being burnt up by your engine that is bad news.

When you purchase coolant at the store, you can get a prediluted mix or a concentrated coolant. It’s cheaper to purchase the concentrated coolant and dilute it yourself with a 50/50 mix of coolant and water if you are replacing a lot of coolant at once. Use distilled water in order to keep your cooling system free of any impurities which may cause clogs or blow-outs. Having a spare pre-mixed container in your car in case of emergencies can be very handy.

Power Steering

Last but not least is your power steering fluid. Not unlike your brake fluid, your power steering fluid is a hydraulic medium which lets your steering wheel communicate with the front wheels to aid you in steering your car. Power steering fluid is usually dark red in color, similar to ATF.

Just like ATF, you will only need to change it every 50,000 miles. If you hear a whining when you turn your wheel to the extreme in either direction, or you’ve noticed your steering wheel has become harder to turn, you should check the level of your power steering fluid. Some cars will have a power steering reservoir that has markings on it, but most cars will have a short dipstick on the underside of the cap of this reservoir. Check to make sure you are filling to the correct level, whether it’s cold or at operating temp.


If you are checking your fluids and you notice something is very low, you likely have a leak somewhere in that system. Learn to identify the different fluids based on their colors or scents. If you notice the fluid getting low often or puddles of a certain fluid under your car, check in with your mechanic. If there is a leak, you will want to identify it, but if you don’t see any obvious signs and need to get to work, top off that fluid and get going. Keeping these fluids topped up, even if they are leaking, will not only save you a lot of money in towing bills, but also from driving your car into the ground prematurely and creating unnecessary waste.

Got questions about your car, truck, SUV, or other engine-powered vehicle?

illustrations by Deanna Larmeu

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