Car blowing huge amounts of white and blue smoke?

[Jessica D]

It's a 2002 volvo s60 with 85,000 miles. A few days ago it started smelling very strong of gas fumes, especially when it was first started. Then a couple days later it started blowing blue smoke, but seemed to run fine. Now it blows massive amounts of white (with a bluish tint) smoke out of the tailpipe non stop. It runs rather rough, with occasional back firing and low idling. It is burning through a quart of oil an hour with no obvious leaks, except out of the tailpipe. I replaced the seal on the oil filler cap, but that seemed to have no effect at all. Any cost effective suggestions on where I go from here? Any help would be much appreciated! Thanx