Using oil in my 2005 Prius -

With that many miles it could be one or more of about 15 things that get worn in your ICE with miles and using a quart every 2,000 instead o every 200, it might not be obvious where it's going.
Front or Rear Main Bearing Seals, Worn or Damaged Main Bearing, Worn or Damaged Connecting Rod Bearings, Worn or Damaged Camshaft Bearing, Worn Crankshaft Journals, Tapered and Out-of-Round Cylinders, Distorted Cylinders, Clogged “PCV” Valve, Honing Abrasive, Worn Ring Grooves, Cracked or Broken Ring Land, Worn Valve Stems and Guides, Bent or Misaligned Connecting Rods, Worn or Improperly Fitted Wrist Pins, Clogged Oil Passages.
Even extremely high mileage Prius taxis eventually reach an end of economic life.
Short of a complete rebuild or new engine, adding oil for those next 50,000 miles might be a reasonable option.
If you're not already using synthetic, you might switch to a synthetic oil like Royal Purple. Some have gotten good results reducing oil consumption on very high mileage cars with it.

 

I'd say with that amount of miles you don't really have a problem. I might be wrong but technically I don't think it's considered a problem until you start using a Qt. every 500 miles.

 

You can also try something like Mobil-1 5W-30 High Mileage Formula

 

Oil burning creates blue smoke, more pronounced when accelerating if it's the bores, pistons or piston rings and more pronounced on pick up after deceleration (engine overrun) if it's the valves, valve guides or valve stem seals. Black smoke is over fuelling.
As said above 1 quart every 2000 miles is not too bad
You could try a higher hot viscosity oil, say 5W40 instead of 5W30.

 

I would say that using to much in high amounts of oil in most cars is not always ideal but the first thing I would do if I were you would be to find out where the oil is going. I can tell you at least though that If it was burning oil than
you would probably see it in the exhaust. It would be a good idea just to be on the safe side if you are planning on taking it in to have the auto shop run compression checks, inspect seals, and to check your car`s
coolant for oil .

 

If you're sure it's not leaking then it's got to be internal consumption, typically getting past the rings and/or the valve guide seals. To be honest, a certain amount of internal oil consumption is to be expected with an engine of your mileage.

Yes this in my opinion.

It's not clear whether or not you've managed to make it this far while always topping off the oil in time (that is, never running it below the lower dimple on the dipstick). If you have run it low one or more times then this will no doubt have exacerbated the issue.

In any case, if you're now at about 1 qt per 2000 miles then that's still fairly manageable, particularly if you're only looking to get about another 50 kmile out of it. Just use a high mileage oil (no thinner than 5w30) and make sure you never run low. Check it every tank fill and top off as needed, you'll probably be fine for more than 50,000.

 

1 quart used every 2000 miles is phenomenally low oil consumption for an engine with 267k! Put in a quart between changes and don't worry about it unless it gets substantially worse.

 

In the handbook for the Prius+ (v) it states a quart every 600 miles is the limit of acceptable, so you've plenty to go yet.