Wacky oil consumption, and rare dropping to 3 cylinders

[musketeerracing]

Anyone able to help with these?

1. Most of the time my 1990 2.2 Legacy AWD 5MT consumes very very little oil. Like I changed it and more than 2000 miles later it was still on the full mark. But then occasionally, over a single tank of fuel, it will go from full to essentially empty. What's up? There's not like a check valve or something that moves the readings around the map, is there? My level checking is usually consistent: flat surface, 5 mins or so after shutting the car off, etc. What gives? Not burning oil that I can see, and no leaks I can see.

2. Twice the car has dropped to three or possibly even two cylinders. Both times have been in heavy rain and at fairly high rpm. I would suspect a coil pack or similar but it blows blue smoke in a big way when this happens. Dropping spark should give me black smoke if anything, right? Blue smoke says rings/valves but why should this happen in the rain in particular? Humidity?

Wacky questions, I know. I look forward to your answers.

PS oil level change and dropping to 3 cylinders to not correlate temporally.

ACP

[NICO]

i would say your on your way to getting a blown piston.

[musketeerracing]

Wellllll, thought of that, but I've never seen an engine limp then self-correct with a piston problem. I did probably 3000 miles (in a month) beween the limps. I thought maybe a cracked ring that separates and comes back together, or possibly a sticky valve. The former might explain the blue smoke while the latter might not.

In my experiance holed or cracked pistons allow the crankcase to pressurise and the first thing is you smell oil. But then every engine I've blown has been on 23lbs of boost so maybe a NA engine goes differently??

A.