No engine is completely perfect when it comes to burning the mixture of gasoline and oxygen that is directed to the pistons. In almost all vehicles, its inevitable that this system will result in a buildup of excess gas and vapors that simply didn't burn. This gas typically escapes the piston and enters the crankcase, which houses the crankshaft.
Essentially, this unwanted action can cause all types of problems for an engine. It can begin to chemically degrade the oil, hurting its lubrication ability. It may also cause the oil to build up and turn to sludge, which can eventually cause oil to get in other areas of the vehicle and begin burning. This can do serious damage to your engine and emissions system over time, so it's very important that the vapors that accidentally enter the crankcase are effectively vented.
Enter the positive crankcase ventilation (PCV) valve. This small part is built in order to periodically let out the vapors and gas that builds up in the crankcase. The valve opens to release the vapors into a hose, which then goes back to the intake manifold. The intake manifold leads to the engine, allowing this gas to be reburned and used again. Essentially, the oxygen and gasoline that escapes the pistons initially is forced into a loop so that it will get burned eventually.
Thus the PCV valve is a very important part of a functioning engine, but not well-known enough for many drivers to pay close attention to. Typically, a PCV valve is only noticed if a problem arises. The part doesn't tend to wear out on its own, but could become stuck in an open or closed position if the oil is allowed to turn into sludge. This can infest the PCV valve and eventually plug the valve up. Paying attention to your oil changes and getting them done at timely intervals will prevent this problem, among other issues.
But if you've been ignoring your oil changes, it's entirely possible that you'll need a new PCV valve. Fortunately, this is an easy piece of maintenance that most drivers can perform on their own.
The first step is locating the PCV valve. On some engines, this is incredibly easy - it may be sitting in plain sight on top of the engine in easy reach. Other models make it a bit more complicated. The valve looks like a plug and will be attached to the crankcase. If you're unsure, be sure to check your owner's manual for its exact location.
Many people replace the hoses that the valve is connected to at the same time, and in fact some PCV valves are sold with replacement hoses. This is a good idea because on some models, you'll actually have to remove the hose anyways in order to get to the PCV valve in the first place.
Replacing the PCV valve is sometimes as easy as removing the old valve by hand and inserting the new one. However, you may need to use pliers to get a good grip on the valve, especially if its in a tricky place.
Inserting the new valve can also be a bit tricky, and it may need a bit of lubrication in order to fit into the hole. What's the best lubricant for this situation? You guessed it - motor oil. It's supposed to be in this part of the car anyways, so it's really the only thing that you should use in order to lubricate the valve opening. Using anything else risks damaging your engine.