Changing your engine’s oil is one of the most important things you can do to keep the heart of your vehicle healthy, not to mention prevent extremely costly repairs down the road. We’re going to tell you how to do it, and also why it’s so important. Use this as a general guide and refer to your owner’s manual or shop manual for more information about any specific procedures that might apply to your vehicle.

Your engine is under extreme stress and its internals move and rotate very quickly. A typical engine contains many metal parts that move extremely close together thousands of times per minute. As the oil travels around the engine, it creates a film in critical areas that actually separates metal parts from touching each other. Without this barrier, the engine would quickly (and literally) grind to a halt.

Over time, heat and contaminants degrade the oil, reducing its lubricating properties—which can cause increased wear on the engine’s internal components. The oil filter, which is replaced at each oil change, also helps by physically filtering out various contaminants to keep the oil as clean and slippery as possible. At the end of the recommended oil change interval, the oil and the filter are generally pretty dirty and should be replaced together.

The type of oil you need to use in your car is clearly indicated in its owner’s manual—and sometimes right on the oil fill cap in the engine bay. It shows the recommended viscosity (the thickness of the oil) in a format like this: 5W-30. There might be a second viscosity recommended for climates with very high or low temperatures. Just go with what the manual tells you. Choose a high-quality oil with a seal from the American Petroleum Institute (API), which looks like this:

There’s more reading about oil viscosity and additives below if you’re curious.

There are also conventional and synthetic oils, blends of the two, and specialty oils for various applications like “high-mileage” oil. Debates rage over the “best” oil to use, but the oil that is specified in your manual is a safe bet.

In the vast majority of all cars on the road today, oil is stored in an “oil pan” which is at the bottom of the engine. There’s a drain plug there to remove the oil. The drain plug may be located behind a plastic “undertray” or splash shield that may need to be removed. These generally unclip or unscrew, and add a few minutes to the job. There is also an oil filter, which is a metal canister that filters the oil. It’s usually screwed onto the side of the engine, or located nearby in the lower engine bay. A few vehicles use a style where you remove a lid and install a bare filter into a housing. Refer to your manual for more details.

Oil is filled through a cap that’s sometimes right on top of the engine or located at the end of a fill neck nearby. An oil dipstick is generally used to check the oil level after the oil is refilled, although some cars use an electronic sensor with a different procedure.

Generally, you’ll need the following (and exact quantities and part numbers are available in your owner’s manual):

Changing your oil is a simple job that requires few tools, but it can be messy. Wear old clothes or coveralls, and prepare for leaks by protecting the surface underneath your vehicle.

Possibly. You may need the following if your car is too low to get underneath to access the oil filter and drain plug. Use safe vehicle lifting techniques on a flat, hard surface. Raise the vehicle so it’s level. See this article for more information.

The largest cost in a typical oil change is the oil itself. Oil prices range widely, but a car or truck usually needs 4 to 6 quarts of motor oil. Oil prices vary, but generally, a quart starts at $4.00 and goes from there. Special viscosity synthetic oils for some modern cars can be considerably more expensive. Oil filters and drain plug gaskets are generally inexpensive, in the range of a few dollars for a common brand and type. For most cars, you should be able to do an oil change for under $50—sometimes a lot less.

The procedure below is a general idea of what to expect when doing your oil change. As you can probably imagine, we’re going to tell you to follow your owner’s or service manual for the specific steps to follow.

1. It’s better to change the oil when it’s warm. Take the vehicle for a short drive until it’s fully warmed up, if possible. Use caution as the oil will be hot and may cause burns.
2. Access the underside of the vehicle. If this requires lifting, chock the wheels and lift from the indicated jack points.
3. Loosen but do not remove the oil drain plug. Place an adequately-sized pan underneath to catch the oil.
4. Drain oil completely. This may take a few minutes.
5. Replace the drain plug with a fresh gasket. Use the torque wrench to reach appropriate tightness. If you don’t have a torque wrench, you can tighten it by hand and then “snug” it with a slight turn of a wrench. Don’t overtighten, you might strip the oil pan threads which could be an expensive repair.
6. Move the catch pan beneath the oil filter, and remove oil filter, which should contain a small amount of oil.
7. After oil finishes draining from filter mount, put a small film of fresh motor oil on the new filter’s rubber gasket.
8. Tighten oil filter by hand. Do not use a wrench, you might over tighten it. Firmly hand tight is fine.
9. Refill oil to the amount indicated in the manual.
10. Run the engine, check for leaks at the drain plug or filter.
11. If there are any leaks, check the drain plug torque and the filter.
12. After any leaks are addressed, use the dipstick to check the oil level. Remove the dipstick, wipe it clean with a clean towel or rag, and reinsert. Then remove it to read. There may be a “cold” and a “hot” scale, use the cold one.
13. Take the car for a drive to warm it up. Turn the car off and wait 5 minutes for the oil to settle back down into the oil pan. Read the dipstick on the “hot” side. Add oil if needed.
14. Take your old, used oil to an oil recycler. Many auto parts stores will take old oil for free.

Adding too much oil can be a problem. First, confirm you’ve read the dipstick correctly—they can be hard to read. If the oil reads considerably over the full mark—let’s say you added six quarts of oil to the car and then realized the manual called for four—unfortunately, the best thing to do is remove it. You could carefully drain the oil into a clean oil pan and carefully pour it back into the engine, or drain it all out and refill your car’s engine with new oil.

If there’s too much oil in the engine, it can foam. Foam significantly reduces the oil’s lubricating qualities. Remember, it should form a nice film that acts as a slippery barrier. Foamy oil doesn’t, and could cause serious engine wear. Foamy oil can show up as a light yellow foam on your dipstick.

We think oil is fascinating, and knowing a little more about how it works and the different types of motor oil available will help you make good decisions about what to choose. You’ll notice there are two numbers in most engine viscosity labels, like 5W-30 or 10W-40. That’s because modern motor oils are made to flow easily at low temperatures, reaching and protecting critical engine components quickly when you start up the vehicle but don’t get too thin to protect the engine at higher operating temperatures. “Straight” viscosity oils exist, like SAE 10W or 30, for very specific applications and aren’t used in most vehicles.

Oils also contain a number of additives to make them do their job better in the harsh conditions inside an engine. This includes chemicals and minerals that help with lubrication, help prevent the oil from breaking down over time and detergents that help keep various components clean of contaminants. API-certified oils are required to meet certain additive package requirements. An API-certified oil in the right viscosity should meet your engine’s requirements for additives, and your manual will provide more information. Companies do market additional additives that can be added to engine oil, but their efficacy is debatable.