I have run my car with ported heads, cam, and longtubes for 3yrs now. I have a total of 24k on the car and 10k on the heads, cam. The car has never used a drop of oil, even when I autox it a lot. I put the car away in october last year and it sat all wintert. In april I went to take it out of storage and found that mice had moved into the HVAC system making a mess and a lovley smell. So the car goes directly to the GM dealer to have the vent system cleared out and fan replaced. I then pick the car up and make it 400 yrds out of the dealership when a suspension part fails and the car has to be towed home. It was a simple fix and the car is back on the road, but I notice that as soon as the car is up to operating temp the idle stays high when the car is moving.
I then sold the 12bolt out of the car so it was up on jackstands for 2 months waiting for the new 9in to be delivered and installed. I get that done and now I notice that the exhaust is coated with oil and it leaves a soot stain on the floor when reved inplace in the garage. The car also blows a cloud of smoke on startup. The car still feels like it allways has, no loss of power.
I then take the car for a 4hr ride down to kooks to have a new headers and a true dual exh made for it. When it comes out of the shop for a test I notice that it is blowing a bunch of blue smoke at idle, none that i can see when driving. I drive it the 4hrs home and it runs fine other than the high idle.
So today I take it out to go to a cruse nite and the low oil light is on. The car is 2 qts low!!! I look into the new exh tips and they have an oily soot coating in them.

What could have changed over the winter that would cause this sudden oil burning?

 

Start isolating, check out the pcv system first, its the easiest. Oil can only get into the chamber a few ways so start with the easiest.

 

I would trace the PCV system from the intake manifold to the back of each head. I also have a 99 SS and all the rubber pieces in the PCV hose went bad recently. I was using oil, the rubber y piece that splits to the rear of the heads was leaking oil on the back of the tranny and was causing the car to smoke, the rubber piece that connects to the intake mani was bad and it caused an air leak that made the car idle differently. I just replaced all of the rubber pieces with 3/8 hose and the problems are gone. I might even eliminate the PCV system entirely and add a breather.

 

As said check the pcv system. After that I would proceed to a leak down or compression test. Look for a minimum of 170psi on each cylinder and try to make sure that no cylinder is 10% less than the 2nd lowest psi cylinder. The leak down is honestly the better way to check but involves an air compressor. It will pressurize you chambers and then the gauge will give you a percentage of leak. I forgot what is the maximum leak you should allow but I think its 15%. If you can hear air in the exhaust pips you exhaust valve is not sealing. If you can hear air in the throttle body your intake valve is not sealing and if you can hear air in the oil cap area your rings are the culprit.

 

I'd be willing to bet with it that bad you broke a ring land on piston #7. What kind of tune do you have?