Thanks for the help everyone.
I checked the car out, it's got some light body damage but being black, it's hard to tell.
I ruled out structural damage as best I could, looks like the collisions were external sheet metal only. The cooling module appears to be OEM and radiator support original as well. Body gaps are fine except the lower part of the front bumper is cracked / bottomed out.
The owner is a Toyota Tech and it was his daughters car. I presume that would mean he took care it pretty well. He confirmed new alternator in the past year with recent brake work. Drove fine, mostly quiet, did figure 8s in the cul-de-sac (lol) confirming CV joints are not bad. Even wear on the tires and steering seemed straight though the winding neighborhood roads were hard to reference straight tracking.
I've got some experience with multiple 2AZ vehicles, as well as couple xB & tC Scions.
- Chances are - exhaust will be cleaner than expected, but it may still be a heavy oil burner. Had that.
- Blue smoke on startup not likely, unless valve guides are shot. But WOT is a good plan.
- Sludge under oil cap highly unlikely. If an oil burner - it gets enough fresh oil through to keep itself clean.
- Oil level and oil color also can't tell much. On one I was certain it's a burner, yet oil level never dropped after purchase. On another I was certain it's a good one, yet it burned oil like a fast food restaurant.
You called it.
Oil cap looked clean, no smoke on startup or WOT. Engine oil looked new. Exhaust a little sooty but not horrible. Toyota tech dad confirmed 1 quart of oil every month, which appears to be 1000 miles / mo based on Carfax trend and local college commute.
The 02 sensor was replaced but still throwing a MIL, owner claims its the heating element not working in the 02 sensor??
The car skidding TRAC/VSC light is illuminated permanently. The owner says this light always comes on when the MIL is on (due to the O2 sensor). I am a bit skeptical of this, thoughts?
Just go in expecting a crazy oil burner, and you'll be pleasantly surprised if it's not. Realistically - not many signs will give it away, unless the previous owner is honest, good luck with that one. Either way - 2AZ is an awesome engine and Scion xB is an awesome car, regardless of the oil consumption. Keep it topped off. On my 2008 Scion xB the Valvoline Restore and Protect 5w30 completely fixed the oil consumption, but that oil struggles to go past 3000 miles without making the timing chain and valvetrain sound like it's running dry. So use Valvoline Restore and Protect 5W30 with 3000-mile intervals, until oil consumption is gone. And then stick to something in 40-grade with reasonable intervals, this engine loves 40-grade.
Or for the oil consumption there is always the route of Berryman B12 week-long piston soak. If that doesn't fix it - nothing will.
I'm fine if it burns oil all said and done, a quart a month is fine with me.
I will of course follow your instructions and try out the piston soak and switch to Valvoline Restore and Protect.
At that mileage you may have wheel bearings going out. Listen for roaring, it should be apparent.
No obvious groaning.
Is this the fuel additive from Yamaha? I presume use it as intended or straight down the spark plug hole like B12?
Your plan is good, should take care of at least most of the oil burning.
, compared to Project Milan
last longer 
