How to Properly Check Oil and Transmission Fluid in Your Car

February 2nd, 2016 by


Checking your vehicle regularly is vital if you want to avoid looking for a car maintenance service department later down the road. A part of regularly checking your vehicle to keep it healthy is checking your fluids; in particular, your oil and transmission fluid. The oil and transmission fluids are both considered to be the life-blood of your car. Without them, the car would not run properly, and the engine and transmission are prone to damaging themselves if there is not enough fluid for either one.

Before we learn how to properly check your oil and transmission fluid, it’s important to understand what both of these fluids are.

What is Engine Oil?

Engine oil is a very complex fluid, and is comprised of two basic components — base oils and additives. The base oils are what make up 70 to 85 percent of the total, while additives complete the last 15 to 25 percent.

All these additives are known collectively as a Performance Additive Package, and this package is made up of detergents, dispersants, anti-wear additives, friction modifiers, and much more. Understanding what these additives do is understanding what the engine oil does for your car, so it’s important to know a few.

The dispersants are extremely important, and they help keep sludge from forming on the internal engine parts; they suspend any contaminants in the oil until they are safely removed at the next oil change. The detergents are an additive that operate at high-temperature surfaces, and these help prevent build up and deposits, keeping your engine free of debris. Another important additive are the friction modifiers, which do just that; reduce the friction under high temperatures. This helps keep the efficiency and overall performance of the engine in peak operating condition. Finally, there are anti-wear agents, and these form a protective coating on metal surfaces inside the engine. These also operate under high temperatures, and prevent metal-metal contact inside the engine, otherwise damage could occur.

These are only a few of the additives inside engine oil, and they are all there to help protect and enhance your engine. Most of these additives will break down over time, and eventually wear out. Therefore, it’s important to check and change your oil regularly; because these additives are refreshed with each new quart of oil.

What is Transmission Fluid?

Transmission fluid, also known as Automatic Transmission Fluid, is used in automatic (self-shifting) transmissions. Essentially, it acts as a lubricating liquid for all the moving parts inside the transmission. It’s there to keep the friction to a minimum, and keep the internal temperature cool. It’s a lot less complicated than car oil, seeing as it’s principal purpose is just to lubricate and keep the internal temperature of the transmission down. Which is why it’s important to monitor your transmission fluid  regularly, and to ensure there is nothing wrong with it. If there is, the transmission could overheat or have too much internal friction; both of which severely damage it.

With the basic understanding of oil and transmission fluid, now it’s time to get into how to properly change both of them.

How to Check Your Oil

Properly checking your engine oil isn’t a monuments feat; but it is possible to do it wrong and get an inaccurate reading. Therefore, it’s important to follow these simple steps in order to get the most accurate reading possible.

Step 1: There are two things that make up step 1; the first is making sure your car is on level ground. If it isn’t, the oil will congregate on one side and the dipstick won’t be able to give you an accurate reading. The second part is making sure the engine is cold, this way you don’t burn yourself on any hot parts underneath the hood, and most oil checks require the engine to be cold for a proper reading. Some owner’s manuals might tell you to check the car after the engine has warmed up slightly. If that’s the case, just be sure you don’t end up burning yourself.

Step 2: After you have made sure your engine is cold, and the vehicle is on level ground, it’s time to find the latch/button that opens the hood. After popping the hood, locate the engine, and you should see a cap with “engine oil” on it close by. After you’ve found that cap, you are in the right area for the dipstick. Once you find the oil dipstick, it’s time to move on to step 3.

Step 3: Once the dipstick is located, it’s time to remove it. Grab the top of the dipstick and pull it out. Now that you have it in your hand, it’s very important you wipe any oil off the end. This oil is there from when the engine was running, and will therefore provide an inaccurate reading.

Step 4: After you have thoroughly cleaned the end of the dipstick off, it’s now time to put the dipstick into the tube, and then pull it out again to check the oil level. It’s important that you keep the dipstick held straight down or level; do not tip the end up in order to look at it. This will cause the oil to run up the dipstick, and give you an inaccurate reading. There are generally two markings on the dipstick, and it’s important to identify them both: one is the minimum marking, and the other is the maximum marking. If you are between the two markings and inside the crosshatched area, your oil level is fine. However, if you are below the minimum mark, you need to add oil.

Make sure the engine oil isn’t a light-milky brown color or black; you want it somewhere it to be dark brown. A light-milky brown color means there is something leaking into the oil, and black means the oil is in need of a change, and those additives in the oil have most likely worn out.

How to Check your Transmission Fluid

Checking the transmission fluid is quite similar to checking the engine oil; but there are a few differences.

Step 1: Just like with checking the engine oil, make sure your vehicle is parked on level ground. However, the engine temperature is typically reversed. To get a proper reading on transmission fluid, the engine needs to be warmed up (some are checked with the engine off, check the owner’s manual first to be sure).

Step 2: Locate the transmission fluid dipstick (typically the only other dipstick other than the oil dipstick) and then pull it out.

Step 3: After the dipstick has been pulled out, it’s important that you wipe it clean just like the oil dipstick, and then put it back in the tube. Be careful of the fluid, it might be hot.

Step 4: Pull the dipstick out again, and make sure to keep it pointing down or level. Now, pay attention to the markings. These dipsticks typically have two markings; one for “warm” and one for “cold.” If the engine is running and it doesn’t come up to the warm line, you need to add some ATF in order to fill it back up. If it looks like a dark brown color, that means your transmission needs to be changed. ATF should be a clear pink color if it’s healthy.

You successfully just checked your transmission fluid, and it’s time to put the dipstick back in if it’s all set. If not, you are going to need a funnel to pour the ATF down the tube you pulled the dipstick out of. Unlike the oil, where you will add it directly to the engine after finding the cap labeled “oil.”

Important Closing Thoughts

Both of these fluids are there to protect your engine/transmission, and keep them working properly. That being said, it’s very important that you adhere to the markings on both dipsticks. Overfilling of either, especially the transmission fluid, is just as dangerous for your engine/transmission as letting it run dry.

Also, your engine will take different types of oil with the change of the seasons. For the colder months, you will need a thinner oil. Why? Because in the colder months the fluids inside your car thicken, and it takes them longer to cycle through the transmission/engine. Therefore, it’s important that you let your car warm up in the colder months, so these fluids can get to where they need to go.