It would be nice to know what kind of oil had been used in it previously. You see, synthetic oil has cleansing properties and when introduced to crankcases gunked up with crud, the new oil begins to break it down and clean it out. The problem is, that gunk is now flowing through small oil passages and clogs up the AFM screen under the oil pressure sensor at the back of the manifold and sometimes the AFM solenoids which leads to lifter failure. Yours was spec'd from the factory to run Dexos full synthetic oil so if records are not available, assume that is what was run and you should be good.
At 164K, hopefully the transmission has been serviced at least once and should be every 40K or so with nice clean fluids. If it's a 4x4, change the other fluids as well. We have seen them go to 410K with proper service and even that one was driven into the shop for overhaul!
This is about the mileage when things happen, transmission solenoids need rebuilding, the oil pump o-ring goes bad, suspension overhaul required, etc.
Mine is at 164K and runs like a top and we just rebuilt the front and most of the rear suspension.
Maintain your parking brake, if you don't, it'll quit working.
If the Tahoe is a 4x4, you'd be surprised that it too can go hunting, fishing, shooting and hauling! Is it a Z71 by chance?