Sell it AS IS
Include "engine uses oil, cause undetermined" because it IS undetermined, its not a weasel word
Even the mechanic couldn't say why its using oil, just guessing
Valve guide seals, would be my guess
Rings would be a stretch in my opinion, just leave dipstick out and start engine, if there is alot of blow-by out the dipstick tube that would point to ring issues
Turbo, should be a smell in the engine bay, I would think
As for the car flippers, that's not up to you
If you buy a used car/truck without an inspection then that's on you, the buyer
"There is a sucker born every minute, and two to con him"
"A fool and his money are soon parted"
"A fool and his money were lucky enough to get together in the first place"
These quotes are remember because they ring true
caveat emptor, latin for "let the buyer beware" this was first seen in print in 1600's but has been around alot longer
In my opinion it originated when people first started selling and buying, or trading

And its a Legal term, AS IS in a sales contract means there is no implied warranty, caveat emptor
Anything said verbally is off the table once a written contract is made