I have a B230FT engine with low compression in the front 2 cylinders (~100psi). The back 2 cylinders are at 125-130psi. When i dumped about 1/4 cup of oil into the 2nd cylinder, its compression came up to 120psi. I'm thinking bad rings in the first 2 cyclinders, but I thought that all 4 would be the same if rings were bad. If there is a blown head gasket between cylinders 1 and 2, could the oil have temporarily sealed the gap, causing the compression to come up? Other facts-
184K miles on engine, no sign of coolant in oil, all 4 plugs had cruddy, moist electrodes, there are wisps of smoke coming from the valve cover when I remove the oil cap (burning oil). Looking at the camshaft, I didn't see any significant gaps between the cam lobes and the tops of the valves (sorry, I don't know the terminology) when the valves should be closed. I guess the best way to determine if it's the head gasket is to just take the head off, but does anyone have any ideas on other simple ways to determine what the problem is? Thanks.

Bad rings are fairly rare. Did you run out of oil?

A head gasket failure between #1 and #2 would not respond to adding oil.
The blowby condition indicates combustion gases entering the crankcase. You may have broken rings, not all rings break at the same time. The PO may have neglected the intake system allowing abrasives to enter the engine. It doesn't take long for dust and sand to take out the rings (and cylinder walls)!

The turbo inlet hose is prone to fail due to the oil vapors from the crankcase ventilation system coming in contact with the rubber hose.

You might check the rings for sealing by pressurizing the cylinders and checking to see how fast the pressure is lost and listening at the oil fill for any differences in the sounds. Kind of a leakdown test.

My block was so bad it had to be sleeved back to standard from the failed intake hose. The PO did not catch the problem.

I bought the car this summer. The owner said the turbo was bad and was the reason for high oil consumption. (I have posted other questions about the turbo.) I have replaced the turbo and noticed the burning oil fumes from the oil fill opening when I started it up, which led to looking at the plugs and checking compression. So I don't really know the history.

How about doing a leak down test to find the cause before taking it all apart?
Increased compression after adding a bit of oil to the cylinder indicates a ring problem, but not a head gasket problem.
Good luck.

unless it was a fairly minor problem (which it sound like at 100 psi still) and the oil just filled the cylinders up...thus raising the compresion...he did day 1/2 CUP of oil...that would raise the compression anyways...

interstingly my no1 has always been lower too...

and i go thru oil like theres no tomorrow. but only under prolonged boost...

me i think i have shafted inlet valve seals and prolonged boost=higher revs which pumps more oil and this fills the valve train higher..thus it covers the inlet seals and leaks into the manafold...but thats all anotehr story....

gota figure out how to cobble together a leakdown tester...