I have a 2008 volvo s40 2.4.i and have noticed that it is using a lot of oil. When I checked the tailpipe that there was oil there. What could be the problem?

 

Generally there are two ways oil can find its way into the exhaust on an NA engine - a bad headgasket/cracked head or bad rings/valve guides/seals which leak oil into the combustion chamber. Either will require a tear down of the engine. Did you also check the coolant for any signs of oil mixing as well or do any other inspections? What I would do is start by checking out whether the car is producing any bluish smoke then I'd check for any oil leaks/spotting. Next pull the plugs to inspect for color (should be a dry tan/brown not a wet black). After that I'd a coolant HC test (kits available for about $40) then a compression test - do with a warm engine, both dry and wet tests. if the compression is low dry but normal wet, I'd suspect bad rings. If the compression is good across the board, I'd suspect the head/valves. If its bad on one or adjacent cylinders, I'd suspect a head gasket issue. BTW, what do you consider excessive? if your consuming less than 1 quart per 1000 miles, your "oil" may be a combination of soot+condensation not oil.

 

Thanks will check this out. What mad me check the tailpipe is that the car was making a noise when idling. I opened the oil cap and the noise went away. I put the cap back and the noise returned. Could this be caused by faulty PCV valve?

 

Yes. Over pressure of the crankcase due to a bad PCV system. The pressure pushes the oil to places it does not belong.