Volvo S40 Forum : “2002 Volvo 1.9T Oil and Filter Question”

I believe it's a cartridge filter located near the front of the engine block.  A cup style filter wrench is best for getting them off but it's kinda an odd size.  The filter housing I believe has a small drain plug on the bottom of it.  I think it takes a T45 to remove that...  Make sure when you replace it that you get it all the way up...  The seal wring tends to bind and prevent it from going all the way up, which can cause leaks or lose of the bottom of the filter housing on the road.  Clean the threads before you reattach it and only go slightly more than hand tight the threads for the housing caps are fairly weak and can get stripped easily.
As for replacing the filter well... just pull on the old one and click the new one in the way you pulled the old one out.

As for oil and weight of oil I don't know.... about 5 quarts of 5W30 I would think, but check your manual or call the dealer to be sure since I don't really do this kinda thing anymore and it's amazing how fast your forget it all.