if you suspect rings, the next thing to do is a compression test.
got a compression tester? good.

now:
remove all 4 spark plugs.
thread the tester in plug hole #1
with the gas pedal to the floor, spin the engine over 4 or 5 revolutions
read the guage
repeat for the other 3 cylinders.

if any of the readings are low, add a tablespoon (approx) to the low cylinder, install the gauge, spin the engine as before, see if the reading goes up.

if the reading with the oil added (wet) is higher than without (dry), the rings are definitely a problem. even so, you may not have to replace the rings. ive seen rings get stuck from carbon deposits, and they can sometimes be freed up without major surgery.

if the reading doesn't improve when wet, you could have another problem, stuck or burnt valves, head gasket, etc.

low, what is low?

normal atmospheric pressure is 14.7 psi (at sea level) so a compression ratio of 10/1 should read about 147 lbs. because gauges vary and carbon deposits may affect the actual volume of the head, your readings may be more or less, ive seen readings of as much as 190. what you're looking for is readings about 150 or higher, and all 3 close to each other, say 150-170. EXAMPLE ONLY

THEN do a leak down test and let us know the results please

I posted this so we all see the problem and results from the test and to make sure you did it right.
SO I can help you further ....I am pretty sure it's the rings !