How to Change Oil

Oil Field Image Gallery Engine oil lubricates the internal moving parts of your vehicle's engine, neutralizes acid and absorbs heat, too. See more oil field pictures.
© DeLillo

Changing your engine oil is one of the single most important vehicle maintenance acts you can perform. Gasoline, coolant and water, transmission and brake fluid are all important fluids for your car, but no other fluid can have more negative implications on your vehicle's engine if you don't address it regularly. Engine oil lubricates the engine, absorbs heat and allows the moving parts of your engine to work properly with one another.

Over time, heat breaks down the oil and reduces its lubricating properties. Oil also helps to neutralize acid in the engine, but this process breaks down over time. Oil works well to absorb trace amounts of water, dust and combustion byproducts in your engine. However, as heat breaks down the oil, it loses its effectiveness to absorb these materials and they begin to stick in your engine and can cause major car maintenance problems.

Think of your engine's oil like the blood that runs through our bodies. Of course, we don't need to replace our own blood, our bodies do it automatically. But the body does pump blood to all areas so that our various body parts can work correctly. When an area of our body doesn't receive blood, it shuts down. Similarly, when an engine doesn't receive the right amount of oil, or when the oil is so old it doesn't lubricate well, the engine will stop running smoothly and some expensive automotive maintenance may be required.

Checking your own engine oil is one of the easiest preventative auto maintenance actions you can take. On the next page, we'll take a look at how to check your oil's clarity.


Checking Oil Clarity

It's a good idea to occasionally inspect the clarity of your engine's oil.
It's a good idea to occasionally inspect the clarity of your engine's oil.
© Cervo

If you're unsure when your last oil change was, it's fairly simple to judge how far away from an oil change you are by checking the oil's clarity. Think of it like shampooing a carpet. As you clean the carpet, you can see the water change from clear to brown. After a while, the water is no longer clean and needs to be replaced. Although checking the oil's clarity isn't an exact science, inspecting it just might keep you from serious vehicle maintenance down the road.

Your engine's oil helps absorb heat from the engine and lubricates moving metal parts that would otherwise grind together. As you drive, the oil pump circulates oil within your engine and the oil filter catches the deposits that build up over time. The oil filter performs its own type of car maintenance by keeping the oil clean. But as the oil gets older, the number of deposits in the oil continues to build and the filter is unable to extract all of the material. When this happens, the color of the oil changes and it indicates the oil should be changed.

To check the clarity of the oil, let the car run for a few minutes and then shut it off. Find your oil dipstick, pull it out and check the level of oil and its color. If the oil is a dark-brown or black color, like Coca-Cola, then your oil needs to be changed. However, if it appears to be lighter, like the color of a cup of tea, then you still have some time before it needs to be changed. Changing your oil is a quick and easy auto maintenance fix, so don't be intimidated.

If you determine by your engine's oil clarity that it needs to be changed, it's best to not waste any time doing so. Waiting too long to perform this basic automotive maintenance can have serious implications for your engine.

Drain Oil

Before you can drain the oil, there are few steps you need to take to get ready for this minor auto maintenance process. The first is making sure you have the right tools and equipment on hand. To drain the oil, you're going to need a socket wrench; this will allow you to remove the bolt on your vehicle's oil pan. You're also going to need an oil filter wrench and an oil catcher or recycling container to catch and store the old oil until you dispose of it. It's also a good idea to have some rubber gloves, rags and old newspapers as well.

Next, you'll want to drive the vehicle around for a bit to warm up the engine. This allows the oil to get hot and will help it to drain out at a faster rate. Make sure you run it around the block a couple of times or even take it on the highway if you can, anything that will raise the temperature of the engine.

Once the engine is warm, park the vehicle on a flat surface, switch it off and let it sit for five or 10 minutes to allow all the oil to drain down into the oil pan. Some vehicles, like pick-up trucks and SUVs may have enough room for you to get under the vehicle to work, but most sedans and smaller cars won't. When you take your vehicle to an automotive maintenance shop, they can use a hydraulic vehicle lift to easily get underneath. But if you need the extra space, just drive the vehicle onto a set of car ramps or use a sturdy pair of jack stands.

Locate the oil drain plug under your vehicle. It'll be a large nut at the very bottom of your engine's oil pan, usually the closest thing to the ground. If you're unsure where it is, check your owner's manual or ask your mechanic to show you the next time you're in for vehicle maintenance. Use the socket wrench to loosen the nut. Remember that the oil inside is still hot, so instead of trying to catch the nut as it falls off, just let it fall into the oil pan and let the hot oil flow out. All of the oil should drain out in about two minutes. It's a good idea to lay newspapers around the container to make sure excess oil doesn't spill in unwanted areas.

Scott Memmer, from, recommends a basic car maintenance tip of replacing the sealing washer around the drain plug before you put the plug back in. This will ensure that oil won't leak out from the drain plug area. On the next page, we tell you how to change the oil filter.

Change Oil Filter

A car engine oil filter
A car engine oil filter
© Yurkinskiy

The next important step in changing your oil is replacing the oil filter. Remember, the oil filter holds all the excess sludge and grime that the oil catches while lubricating the engine. Changing the filter is vital to car maintenance because without a new oil filter in place, new engine oil will be passing through the old filter, making it dirty and less effective. You can check your car's manual to find out which size filter you'll need. They can be purchased at any auto maintenance shop for around $5, or up to about $20 for performance filters.

When you're under the vehicle draining the oil, locate the oil filter. It will be cylindrical and may be blue, white, black or orange depending on the brand. Use the oil filter wrench, available at any automotive maintenance shop, and turn it counterclockwise to loosen the filter. The old filter will have hot oil inside it so be careful when taking it off. One turn with the wrench should loosen it up enough to twist it off the rest of the way by hand.

Before installing the new oil filter, first take a little bit of clean oil and rub it around the rubber gasket of the new filter. This will help the new filter fit snugly onto the engine block. For good vehicle maintenance, it's also a good idea to use a rag to clean off any excess oil around the area where the filter screws onto the engine. Take the new filter and screw it on the engine block by hand. Once it's snug, tighten it with the oil filter wrench. It should take about a half to three-quarters of a turn to get it firmly in place. Remember, you want the filter on tight, but don't over-tighten it either; you could damage the filter and cause it to leak.

On the next page, you'll learn how to fill your car's engine with the proper amount of oil.

Replacing Oil

Used oil is a hazardous material -- you should always dispose of it properly.
Used oil is a hazardous material -- you should always dispose of it properly.
© Rota

When filling the engine back up with clean oil, check your vehicle's owner's manual or reference a service manual at your local automotive maintenance shop for the type of oil that's recommended and how much you should use. Typically, most engines take between 4 and 6 quarts.

Use a funnel to channel the oil to keep it from spilling out onto the engine. Oil that spills onto the engine could heat up, causing a fire that requires additional vehicle maintenance later. Once you've added the correct amount of oil, lower the car off of the ramps or car jacks. It may take a few minutes for the oil to reach the bottom of the pan because it's cold and moves slower than hot oil. The oil level should be just below the "full" mark on your dipstick. For reference, the amount of oil between the "add" and the "full" readings is 1 quart.

It's extremely important that you don't add too much oil to your vehicle. When too much oil has been added, the crankshaft can come into contact with the oil. The crankshaft spins at several thousand revolutions per minute and can whip the oil into froth. If this happens, the oil pump will be unable to pump the oil into the areas of the engine that need lubrication. This can cause serious problems to your engine and will bring you additional car maintenance repairs.

Once you've determined that you have the correct amount of oil added to your engine, turn the car on and run it for about five minutes to allow the oil to circulate. Once you've done this, check for any oil leaks before you clean up. Remember, used oil is considered a hazardous material and must be disposed of properly. Many recycling centers, gas stations and auto maintenance shops will take used oil and oil filters. Some websites, like, will help you locate a depository in your area.

So how often you should change your oil? Keep reading to find out.

Oil Changing Frequency

Towing heavy loads can shorten the life of your engine's oil.
Towing heavy loads can shorten the life of your engine's oil.
© Bonish

So how often should you replace your engine's oil? Most experts and manufacturers agree that every three months, or 3,000 to 5,000 miles (4,828 to 8,047 kilometers), is the most acceptable. However, some manufacturers like Toyota and Ford say every six months or 6,000 miles (9,656 kilometers) [source: Nagy]. But based on how relatively simple it is to perform this type of vehicle maintenance and how vital it is to your engine, the traditional three months and 3,000 miles (4,828 kilometers) standard is still a good interval for changing out the oil.

There are several schools of thought out there on when to change the oil because oil breaks down at different rates based on its use. For instance, how a vehicle is driven, the environment it's driven in and even city driving vs. highway driving can all affect how long your oil will ultimately last. Extreme temperatures (hot or cold), driving on dirt roads, towing heavy loads or driving your car roughly can shorten the life of your engine's oil.

When your car starts aging, it will most likely begin burning oil, regardless of your driving conditions. This means that you'll need to start checking the engine oil level more frequently to make sure it contains the correct amount of oil or begin regular visits to a local auto maintenance shop to have it checked out. For any car or truck, engine oil levels should be checked every few hundred miles and even more frequently for older cars. Performing this regular car maintenance check-up will ensure that your engine has the proper amount of oil at all times.

Some cars are equipped with warning lights that notify you when certain automotive maintenance needs to be performed. If your car displays a low-oil warning light, don't ignore it. When the light comes on, check the oil level and add the correct amount immediately. Some high-end vehicles are now built with more sophisticated systems that actually let you know when the oil has reached the end of its useful life based on the mileage you've driven and your engine's performance. Again, if your car is letting you know that the oil needs to be changed, don't waste any time.

For more information about changing your own oil and other related topics, follow the links on the next page.

Related HowStuffWorks Articles


  • "How Do I Change My Engine Oil and Oil Filter?" (Nov. 13, 2009)
  • Brauer, Karl. "Oils Well That Ends Well." (Nov. 12, 2009)
  • "Car Talk Service: Oil Changes." March 31, 2005. (Nov. 11, 2009)
  • "The Unofficial DMV Guide - How to Change Your Oil." (Nov. 11, 2009)
  • Memmer, Scott. "How To Change Your Oil: The Real Down and Dirty." (Nov. 11, 2009)
  • Nagy, Chris. "Change Your Oil." AOL Autos. Jan. 27, 2009. (Nov. 11, 2009)
  • "Engine Oil and Filter Change." (Nov. 11, 2009)
  • Wilson, Sue. "Blood in the Body: How is Blood Produced?" (Nov. 13, 2009)