2010 isx burning coolant?

[tree98]

Pressure test the cooling system to 20 psi and look for external leaks, also disconnect the egr cooler so you can see inside it for leaks. If you don't see anything you'll have to drop the oil pan so you can look for leaks from a dropped liner or leaking injector cup.
Don't assume there's no leaks because someone else says so, verify it yourself.
Using that much coolant should be easy to find it.