What's Causing This??? Another P0301!

Sounds like a lot of oil burn in that cylinder. Might try a leakdown test.

High vacuum or rpms can pull more oil through a ring/cylinder problem or a valve seal. A leakdown test can tell which one.

I would also swap coils 1 and 2 on the off chance a coil was weak. Just because its easy.

One thing for sure you don't want to drive it with a constant misfire. Buy one iridium plug for cylinder 1.

 

You gotta start making plans for what you're going to do when this car is going to be too expensive to keep repairing!

Your hybrid battery is deteriorating and making the engine work harder. You've ignored my advice for years about leaving your car running all night every night to run the heater or AC depending on the time of year and we already talked about how carbon buildup can foul engines that are left idling for too long.

To be clear, your car camping needs are more than your car is able to provide and fouled plugs every 6 weeks and now 8 weeks is a problem that's going to cost you all the money you've been able to save by living in your car. Get ahead of this problem before it gets more out of control.

A new Sodium-Ion battery would massively reduce the amount of time your engine would turn on and off everynight and then you could use that battery pack on the next Prius you buy when the innevitable engine failure arrives.

 

I answered that question 8 weeks ago, when you first asked. Have you done anything to control the oil burn issue? Your just going to oil foul the next set of spark plugs you install in another 8+ weeks down the road; unless you address your oil burn issue. Did you switch to the thinner 0w30? That might explain some of this.
This coupled with low power is more than likely your engine is worn-out. A good mechanic, with the proper diagnostic tools can tell you for sure - NOT a mobile mechanic. Most of those that I've meet, can barely turn a wrench without breaking something else. Don't get me wrong; most of them can "rubber-band" something together to get your back home - but not an in-depth fix.
Unless you take care of the underlying problem; your just going to continue to have issues.

 

hybridautomotive.com has a FAQ page to explain to you how to restore battery capacity through deep cycling and someone on here can probably loan you the gear.

If I were in your situation I'd put more plugs in and find a place to stay for a week and get it cleaned up and sell it while it still functions and that way the cost of a truck with a camper shell won't be as much.

If someone else owned your Prius and didn't run the car all night every night the vehicle will have a much longer lifespan.

 

Unlike Priuscamper, I am not here to sell you anything and make a commission. Neither is Biomed.

Two quarts in 7 weeks is major. More so if most of it is going through cylinder 1.

A good engine should burn NO observable oil in 7 weeks, ever.

However a leakdown test might tell you its a valve seal. That is reasonably easy for a good mechanic to fix. Parts are cheap, labor might be a couple of hours.

If the leakdown test said piston rings then its engine time, replace vehicle or don't run it hardly at all except to actually go somewhere.

Even then I would get a harbor freight ratchet, extension and spark plug wrench and change that plug myself every 6 to 8 weeks. The plug is cheap.

Luckily its warming up and with a new spark plug it keeps running.

Believe me, this is bad when it happens. The damper between the engine and the transaxle is ready to fall apart and its an engine out repair. Don't run it like this!

It could be a $20 fix if you did it each time. Stopping the oil fouling or getting rid of the car is the long term solution.