2005 starting to use OIL after 180 K

Clean out? Like Sea Foam?

How much oil are you burning? A quart every 2500 miles wouldn't be at all bad on a car with that mileage. A quart every 1000 miles would be annoying.

Some things to try: Change the PCV, if not done in the past 50K, definitely start there if it is the original. Try running a different motor oil. Anecdotes suggest Royal Purple helps. Another guy just posted that Lucasoil Oil Stabilizer helps.

This seems to be a common problem in Prii with over 150,000 miles, suggesting to me that valve seals are worn. If that is the case, then a clean out won't help, but additives might.

 

Some amount of oil consumption would be normal with the car approaching 200k miles. You'll need to post more details on the amount of consumption before we know if it's anything out of the ordinary and what measures you should be taking.