Oil Leak
 

Just bought a 2002 Volvo C70. Changed the oil and filter, drove it for about 20 miles and then started blowing oil out of the left side of the motor. Oil filler cap and filter cap are fine. Anybody else had this problem?

Cam seal would be my first guess - it's usually that on a high (over 100k) Volvo. Picture?

Were you getting smoke out of the oil filler by any chance? That's the classic sign the the flame trap is gunked up creating increased pressure in the engine, eventually the cam seal goes belly up and oil leaks out the side of the engine. Sometimes surprisingly fast.

did you check the oil fill level? double check that the filter and 0-ring were properly installed? if you overfilled its possible the car pushed out a seal. Agree that a clogged PCV system can turn a white block into a bleeder in a hurry. Good news is you can usually just push the cam seals back into place as they can walk themselves out. Another thing to look at is the turbo return line seals. When that small gasket goes, it can make a huge mess.