I'd ask the owner whether or not he/she has installed the updated valve cover assembly that controls oil flow for the Active Fuel Management (AFM) system, and whether or not their truck is using oil.
I've got an '07 LT that started using oil around that same mileage, and it was related to issues with the original design of the AFM oil management system. I had the updated assembly installed at about 140K.
I'm at 225K on mine now, and I started getting a serious AFM lifter noise issue recently (see my post earlier on this forum). The fix would be very expensive (to replace the AFM lifters), so I've elected to purchase the Range Technologies AFM "delete" module. This prevents the engine from operating in V4 mode, and the suspect lifter is quiet in V8 mode - at least for now.
I would highly recommend that anyone owning a lower-mileage AFM V8 truck install the Range Technologies device to prevent V4 mode. I have only run full synthetic oil since I bought my Tahoe new, and have changed oil frequently. While I have significant mileage on my truck, I'm confident that the lifter noise issue I experience now likely would not have happened had I installed the AFM delete unit several years ago . . .
Good luck!