MPG indicator while driving is not consistent

You have to replace the rings and pistons. They are the updated ones.
You probably can't even get the older ones any longer.
It would cost less money and work and time to get a remanufactured engine.

 

Damn, saving gas cost Hell of a lot of
Money!!!

 

Another option, especially if cylinder walls are deteriorating, is a new short block. Part cost around $2000~2500 USD. It will have new pistons and rings. It’s the component between upper oil pan and head gasket. Plus labour, maybe a grand?

I believe this is the part no:

11400-37140

(part no determined on Amayama)

Toyota USA parts site link:

Short Block Assembly #11400-37140 | Autoparts.toyota.com

 

Yeah I’m also seeing one around $1950 USD.

Short block is the “heart” of the engine. The next most significant component is the head, everything above head gasket. Machine shop typically provide a refurb service, clean, inspect and replace seals. @The Critic has a head gasket thread on his experience, linked in my signature.

(on a phone turn it landscape to see signatures)

 

A dealer will not diagnose a weak hybrid battery, they read codes and replace with new if there is a hv battery fail code.

The excessive oil burning is the rings and a dealer will recommend a new short block and rebuild of everything else or will throw in a salvage engine with no guarantee.

If you had a head gasket leak now you would know it from the god awful metal to metal start up rattles on occasion.

Your complaint was mpg.

You will get a full rebuilt engine with a new short block. They have to pull the engine, tear it apart, rebuild the head and clean up everything else. Most would install new water pumps and thermostat as well.

On a car this old with 270k miles with issues, most will move on or will choose a lower cost used hv battery and jdm engine. Normally dealers recommend the move on, let's look at our available cars option.

 

When I did
Do oil changes
At Prius meet ups and saw other oils when I drain other priuses, I knew 10,000 mi oil changes were
Too long of intervals. 5,000 highway miles was the limit. I have 250,000
Mi on mine, still get 500 to 550 mi to the tank.