Check Your Vehicle's Fluids
to Keep it Running Smoothly

To help your car or light truck run better, last longer and function safely you need to check your fluid levels periodically. These include fluids for your brakes, radiator, oil and transmission (as well as others). Follow these simple steps to give you more peace of mind as you travel down the road.

Throughout this article I use words like "usually," "often" and "most." That means that on your car or truck you may not find exactly what I am describing. Refer to your car's owner's manual for specific hints if you are not able to find something I describe below. The manual will also tell you if there are specific fluids needed for your vehicle.


Of course this one is an easy one since you have a gauge on the dashboard. You know you need to fill it when it is empty, but there are times when you should consider keeping it topped up regularly.
If there is inclement weather and fuel service might be interrupted, you should fill your tank and keep it as full as practical. If power goes out for several days the gas stations may not be able to pump gas.

You can use the gas from your car to power generators. However, getting gas out of your car once it is there should be done with care. Use a syphon pump to get the fuel out instead of sucking it out with a hose and your mouth.


Oil is the most important fluid to check for the health of your engine. An engine that is low on oil will not run well and can be easily damaged. An engine without any oil, or extremely low oil level, can be destroyed within seconds of turning it on. Check your engine oil regularly.

Find the dipstick in your car. It is usually on one of the sides of the engine, but it can sometimes be found in the front. The dipstick is a long metal stick that goes down into the oil pan to determine how much oil is in the engine. However, when looking for the dipstick you won't see a long metal stick. You need to look for a (usually) black ring that can be pulled up easily. If you see something you think might be the oil dipstick, give it a gentle pull. If it comes out, then you have found what you are looking for.

Sometimes the oil dipstick is not a ring but a T-shaped handle. In those cases it often has the words "Engine Oil" printed on it.

The transmission fluid dipstick looks similar, but is usually at the rear of the engine. One easy way to tell the difference is that the tube of the oil dipstick is small and can just barely accept the stick. A transmission dipstick tube is bigger around. The oil dipstick tube is about the same diameter as a pencil and the transmission tube is about the size of a fat cigar.

Check your engine oil when the engine has had time to sit for 10 minutes or more. This allows the oil to drain into the oil pan and will give you a more accurate reading.

Pull the oil dipstick out, wipe it off and stick it back in. This will help you get a better reading. Pull the stick out one more time and see where the oil reaches on the indicator. Most dipsticks have a crosshatch section that shows where the proper amount of oil should be. That crosshatch will indicate full at the top of the section and 1 quart low at the bottom. You can figure out how much oil to add based on where it is in that section. If it is below the crosshatch you need to add more than 1 quart.

If you need to add oil do not add more than the top of the crosshatch area. Too much oil can be harsh on your engine too.

Add oil through the oil fill cap. It is round and on the top of the engine. Not the very top in the center, but off to one side. Check with your car owner's manual for the weight of oil they recommend. You don't have to understand the weights, but you should always put what is recommended in there.

Fluid Checking and Filling LocationsCredit: dpeachBrake Fluid

The place to check your brake fluid is on the driver's side of the engine compartment. It is often closer to the passenger compartment than it is to the bumper. It is rectangular in shape, white and has a round lid. Most of the time the lid will say "Brake Fluid."

You can check the level of your brake fluid by looking at the side of the rectangular bowl. There will be indicators on how full it should be and you can see the fluid.

Brake fluid is mostly generic, but you should check with your owner's manual to see if there is anything specific they recommend.

While the engine oil is the most important for the life of the engine, the brake fluid level is the most important for the life of the driver.

Power Steering

The power steering fluid compartment will be similar to the brake fluid reservoir. However, it is usually round instead of rectangular.

Checking the power steering fluid is just like checking the brake fluid. There will be an indicator on the side of the unit.

Some larger vehicles with big power steering reservoirs may have a small dipstick under the power steering fluid cap. Pull the cap off and see if there is an indicator stick if you are not able to see the indicator marks on the side of the tank.

Power steering fluid can be car-make specific. Check your owner's manual for the specific fluid you should buy.

More Fluid Filling LocationsCredit: dpeachRadiator Coolant

WARNING: Never attempt to open a hot radiator cap! When the radiator is hot the fluid inside is pressurized and is close to boiling temperatures if not 40 degrees hotter. When you open a hot radiator the cap can explode out of your hand and boiling hot liquid will spray all over you. Don't do it!

With the radiator cool you can simply open the cap and add water or coolant if it isn't full. Some cars have a side reservoir that you have to fill instead of filling the radiator directly. In those cases there is an indicator on the side of the reservoir to tell you whether you need to add more or not.

If you are adding small amounts of liquid at a time, then adding water is fine. However, if you have to add fluid often or in large amounts you should add a pre-mixed engine coolant.

Transmission Fluid

The transmission fluid dipstick looks like the oil dipstick except it is usually at the back of the engine compartment instead of to the side of the engine. Like the oil dipstick it can have a ring or a T-handle.
Transmission fluid should be checked when the engine is warm, but it doesn't have to be hot. Drive around the block for a few minutes making sure you cycle the transmission through all the gears and use reverse. This helps the fluid to get to where it needs to be so that the dipstick indicator will read properly.

Just like the oil dipstick you should pull it out once and then replace it after cleaning the fluid off it. Pull it out again and read the level. Transmission fluid can be hard to read on the dipstick because it should be light in color. If it is dark and smells burnt you should have your fluid changed.

You should not have to add any fluid, but if you do you will probably need a funnel. You add transmission fluid down the same tube that the dipstick travels in.

Transmission fluid is always car manufacturer specific. Check with your owner's manual.

Windshield Washing Fluid

There is nothing really to check with the windshield fluid level. If it is empty, fill it up. You can use plain water or get some windshield washing fluid from the store. The difference is the fluid has a little soap and a much lower freezing point than water.

Hot or Cold?

Check these fluids when the engine is warm:

  • Transmission Fluid

Check these fluids when the engine is cool:

  • Oil
  • Radiator Coolant

It doesn't matter when you check these:

  • Brake
  • Power Steering
  • Windshield Washing Fluid

Those are the main fluids you will have to deal with and check on a regular basis. You should check your oil at least once a month. While you are at it it won't take long to glance at all the other fluid levels to avoid any problems with low fluids.