An oil pan and socket wrench.Gather all the necessary supplies and equipment. Under your car with all the oil out is not the time to discover what is missing. It will help to have everything close at hand. (Caution: take great care when working with a hot engine.)
The oil drain plug.Before draining out the old oil, you may want to open the hood of the car and open the oil filler cap on the top of the engine. This will help the oil drain easier because air can flow in as the crankcase drains. Locate the drain plug on the bottom of the oil pan. It is normally towards the back of the engine at the car to catch oil runoff. As the oil comes out of the pan at an angle, it can be tricky to catch, and may land on the ground. If this includes your driveway, you will want some newspaper or a drop cloth to catch it, or you risk an oil stain on your driveway or garage.
Removing the drain plug gasket.Loosen the plug counter-clockwise using the proper sized socket (or wrench). The fit is especially important if the bolt is tight, which it shouldn't be. If you need more leverage, an extension such as a pipe segment on your ratchet handle can help. If this type of "breaker-bar" arrangement is required it was way too tight. You should also remove and replace the circular paper (or felt) drain plug gasket, but a metal washer can be re-used if in good condition. Be careful not to drop the plug in the oil, it's a messy job trying to find the plug in the black stuff.
If you do drop it in the pan, you can easily find it with a magnet. Ideally, use the type that is at the end of an expandable rod.
Another easy way to "save" the drain plug is to use a funnel with a bit of screening in it. Catch the plug as it falls out. You can then pull the funnel out of the way of the stream and set it to one side.
The oil filler cap.Some vehicles (such as BMW, Mercedes, newer Volvos, etc) may have a filter element or cartridge as opposed to the simpler spin-on type. They require you to open the cap of a built-in resevoir and lift out the filter element itself.
Remove the filter, using a filter socket or filter wrench if necessary.
Tip the filter into your pan to drain the contents.Locate the filter assembly. This can be a tough part. Filters are not put in a standard position, and they can be on the front, back and side of engines. Look at the filter you purchased to replace the old one and look for something similar. Once you have located it, remove it from the engine. This can be tough, and often seems too hard. They are not supposed to be tight. If it is, once you get a good grip slow and steady twisting can sometimes get it to begin to spin. If you can't get it off by hand, use an oil filter wrench. Keep trying. It will eventually come off. There may be some residual oil in the filter, so be careful not to spill it and have a pan underneath to catch the drips.
When removing the oil filter, make sure that the rubber gasket ring comes off with the filter. If you don't and it sticks to the car, the new filter won't seal properly and will leak.
Lubricate the gasket on the new filter with a bit of oil.When installing the new filter, remove all packaging, then dip the tip of your finger in the new oil and smear it on the gasket ring of the new filter. If you use the old oil, it may contain buildup that will wear away between the gasket and the car and eventually become a leak.
You might pour some oil into the filter prior to installing it. This can reduce the amount of time your car takes to regain proper oil pressure. If your filter is mounted vertically, you may be able to fill it almost to the top. If it is at an angle, you may be able to get just a few tablespoons worth in, just to saturate the filter media. It's actually not necessary if the car has not been stored, there is enough oil left on the bearings to lubricate until pressure is built up; if you'll notice, no garages pre-fill the filter.
Replace the drain plug.Replace the drain plug on the oil pan. Don't forget to install a replacement gasket or washer. Start threading it with your fingers so as not to cross the threads, and it should be snug, but no need to be super-tight.
This would be a good time to wipe any debris or buildup off the surface where the gasket will seat.Carefully screw on the new, lubricated filter, being careful to not cross the threads. With the paper cartridge filters, they will always come with at least one o-ring, sometimes as many as four different ones. Make sure to replace all of them to ensure that they will not leak. The filter will generally say how tight to tighten it. Go until the gasket touches, then however far it says it should be. This is usually 1/2 or 3/4 of a turn after the gasket touches.
A funnel will help.Add new oil to the car at the fill hole. The amount you need is in the owner's manual, usually listed under "capacities". Don't always rely on the dipstick for an accurate measurement; it can be off, especially if the engine has just been run (the stick will read low because there is still oil in the galleries). If you want to check the stick accurately, just check it first thing in the morning, parked on a level surface, when it's cold and settled. It's a relative thing.
If you hold the bottle with the spout on top, as shown, it will pour more smoothly, without bubbling.
Replace the fill cap, check around for tools and close the hood.
Start the engine, watching to be sure the oil pressure light goes off after start-up, and be sure to look under the car while the engine is running (put car in park or neutral with the parking brake on) to check for any drips. If the filter and drain plug aren't tight, they may leak slowly. Run the engine for a minute or so.