A bit of history:
model: 1997 LE NA8 (manual)
has done only 127000 kms
Was bought about 2-3 months ago off a lady onwer who treated it worse than you could possibly imagine. however it was regularly serviced as far as warranty went, she owned it for about 11 years and it had a major service at 100,000. She barely drove it.
There was basically no oil in it when we got it

I serviced it when i bought it (full oil, filter and spark plug change) and recently just changed the oil and filter with fully synthetic 5-30 mobil 1 oil and hit it with a can of suburu upper engine cleaner.
The problem:
The last oil change was done about 2 weeks ago. It has been running perfectly fine untill last weekend. I noticed an extreemly unusually large cloud of smoke come out of my exhaust for approximately 5 minutes untill the car warmed up. At first i thought it may have been because it was a fairly cool morning and the car was cold. My evauluation has now shifted as it has been doing this on every cold startup regardless of the temperature outside.

The smoke is thick, whiteish/greyish, and the car has now begun to chew oil like crazy. On the way home today (50 minute drive) i noticed the white smoke on startup, AND the lifters were ticking as if it were low on oil. When i got home it was dry, i put what was left of my 1l bottle of top up oil in (there was 500ml left) and after waiting for 2 hours the dip stick was still not reading anything.
The biggest thing that scares me is i checked the oil last week and it was fine, (4-5 days after my service) car was running well.
I havent noticed any loss in performance,
thats about all i can think of at the moment,
my thoughts are valve stems or piston rings.
Any other suggestions and input would be appreciated,
Thanks guys