I bought my 2010 Prius hastily because it was cheap and I needed a car soon. I’m pretty good doing basic mechanical work on all my cars and saw this hybrid as a new challenge. Fast forward to me dismantling and cleaning the egr cooler intake throttle body etc. I never really used any oil additives but this Prius had bad blow by and was drinking oil. I tried a couple things off the shelf with no help but recently I tried Prolube and after a couple hundred miles I could tell a difference. I am now 3900 miles into an oil change and have not added a drop. My average MPG is also up over 2 mpg from previous changes before the Prolube. I think I found a new best friend. No I didn’t get paid for this ; just passing along my experience.
Snake oil. You could just be driving different. The ONLY thing that really works, is tearing it down, removing the rings from the pistons, and cleaning. But, you will just have the same issue. So, replacing the pistons and rings is what needs to be done. You could hone out the cylinders, but they are likely not round any longer. So the amount you have to hone, will make the cylinders bigger, so now the rings will be even looser. So at least a short block with the updated pistons and rings. You could try running diesel in the engine, about 1qt to 3qts oil. Though you aren't resolving the problem
