Burning oil

You won't always necessarily "see" blue smoke coming from an engine that is burning oil, especially at highway speeds, where it is most likely happening. Which engine does it have? Has it had regular oil changes? Typically, when an engine all of a sudden starts consuming oil, there's been a major mechancial malfunction. But if it's always used SOME oil. And has just progressively started getting worse, then that just means that it is wearing out. But that's relatively LOW mileage for oil consumption of ANY amount to be happening. If I had to guess, I'd say this engine has NOT had regular oil changes and has probably spent a lot of its life being run LOW on oil. Either way, this is NOT going to be a cheap fix. Good luck.