Spark plugs covered in oil - how screwed am I?

ch1ll said
How Much oil do you use per 1000 miles?
Blue smoke on startup?
Pull valve cover and look at your valve seals. V8’s have neoprene umbrellas, not sure about/6’s. They get old they harden and bust up to pieces from heat cycling.

Compression test will tell you if you have a real problem, followed by a leak down test will give you a good idea what the problem is.

As I said, I drove it like 1400 miles, poured in like a liter of oil already and now the oil level is below "low" already.

No, there is no smoke at all. Maybe a tiny cloud the second after startup but nothing special.
I go try what the other guys said and see if it helped. I really really hope the piston rings are fine ...