I recently replace the oil cooler seal on my 2013 GL350 . Great. I installed a seal under the turbo upside down, and it was leaking oil, so I took it apart and fixed that.

Drove it for a bit with the covers off, no leaks - great!

Was sitting in it idle for about an hour the other day, then ran an errand and an "add oil at next stop" (or whatever) error message came out. Check the oil level and it was low...

Added 1.5 quarts of oil, stuck a scope in and looked around for what I though should be an evident oil leak - none. The ground under the car has some water from A/C condensation, but no oil. Drove some more, still no oil to be found anywhere.

Where's the oil disappearing to? This car has 88k miles on it, which seems low to me...

No add smoke or other things coming out from under the hood.

i initially added 8.25 quarts when i put oil in after the oil cooler change. I then added another full quart - plus what was left in the other one. So in total 10 quarts of oil have gone in since it being totally empty. I did probably lose some when the seal was leaking at the turbo pedalstel - and I didn’t check the oil level again after I changed the seal. But the low oil light was not on. I’m wondering if there’s no issue and it was just low and I didn’t realize until it told me (though it took awhile for the error to appear…)

Note: I have a PCV catch can installed, and there's no oil in it or the PCV line. Also, I replaced the PCV valve when I did the oil cooler seal because, why not (that and it seemed to have failed?)