What should I most worry about

keep a weather eye on the oil level, maybe carry a spare inverter pump

 

My first opinion is always "Just Drive It."

I assume you have been doing the maintenance in the manual.
https://www.toyota.com/t3Portal/document/omms-s/T-MMS-12Prius/pdf/2012_Toyota_Prius_WMG.pdf
The manual only goes to 120,000 miles so you should be on the second pass at 80,000 miles.

[I am assuming you are using a mechanic, if not we can link lots of DIY videos, just say the word, some of these are easy]

Toyota tries new ideas in the Prius (They claim it is Latin for 'it goes before' so it should be where they test ideas.) In the Gen 3 like yours, one idea that did not work out perfectly was the Exhaust Gas Recirculation system. It tends to clog over miles, and when it does, it can cause a failure of the Head Gasket. . (it seals the top of the engine where the valves are to the middle of the engine where the pistons are) You are at a point where I would budget a $1000 to have the EGR system cleaned, so you don't suddenly need a new engine. (or more likely a rebuilt engine)

Both the coolant loops, engine and Inverter should get new SLLC antifreeze. It may be time to have the Brake fluid bled, I would have an expert do that, it is not as easy as most cars. Brake fluid absorbs water, so Lake Placid would need new Brake fluid less often then Manhattan. There are test strips to check if you need it.

Next time it is in the shop have them drain and fill (not flush) the ATF WS, it should be under $150. Do it about every 100,000 miles.

www.amazon.com/Toyota-Scion-Coolant-Antifreeze-Genuine-00272SLLC2/dp/B018Y2WQRK
www.amazon.com/CREACLE-Diagnostic-Testing-Calibrated-Indicator/dp/B07CG89L4P

So take the trip, then start budgeting the rarer maintenance items you may have missed. (In 40,000 miles, new spark plugs)

It is possible you are still on the original 12 Volt battery, but as a rule, car batteries last 5 years. Budget $250 for that when it goes, it is an odd size. The buzzword is Group Size 46B24R. Since the 12 volt battery does not turn the engine, you may not notice when it is weak.

 

I'd just drive it and not "worry" about anything happening just because you're going on a long trip. If something happens, it was going to happen anyway, not because you're going on a trip.
No reason to think it won't do another 6k miles or even another 60k or more as long as normal maintenance has been done along the way.
Good Luck!

 

One reason to watch the DIY videos is you can see what your mechanic SHOULD do. you can see easy and hard and know what he should charge you.

At one point, they were charging $500 for a new light bulb. (If you have small hands it is easier) Watch this Mechanic:

You mention CA, if you need a mechanic near SF Hybrid Repair Specialists - Prius Repair - San Francisco - Luscious Garage

Here is Nutz about Bolts Toyota DIY Playlist, he is very good

Toyota "How-To" videos - YouTube

 

If you visit sites dedicated to almost ANY car brand you will see various horror stories about mechanical failures.
I think the Prius is no more likely to have a melt down than any other car with that mileage.

And carrying around spare parts "just because" probably isn't really a good idea either.

I think a "motor club" membership is a good investment.

 

With over 200K miles you really should get a couple of areas checked. Maybe brother mechanic could have a look, at the Exhaust Gas Recirculation and Intake Manifold. @NutzAboutBolts video #17 and #24 here:

Nutz About Bolts Prius Maintenance Videos | PriusChat

Lots of the other videos tie-in or are of interest as well.

Some info follows, and relevant Repair Manual excerpts attached:

The simplest way to see where you're at, is to check the degree of carbon build up in the EGR pipe, a stainless steel connecting pipe between the EGR valve and intake manifold. Watch @NutzAboutBolts video #16 here:

Nutz About Bolts Prius Maintenance Videos | PriusChat

Two or three other videos linked there too, for the full cleaning of the intake manifold, full EGR clean, and Oil Catch Can install.

Good thread:

EGR & Intake Manifold Clean Results | PriusChat

Another:

Oil Catch Can, Eliminate that knock! | PriusChat

Some tools worth having:

E8 Torx socket (mandatory)
E6 Torx socket (optional, but good to have, to remove the throttle body studs from intake manifold)
3/8" ratchet wrench, regular and long handle, flex head, you can never have enough (or 1/2 plus reducer)
1/4" ratchet wrench, or 3/8" to 1/4" reducer
Ratchet extensions: you can never have enough
Long needle nose piers, straight and bent tip
Ratcheting 12mm box wrench (optional, but makes disconnection of the EGR cooler from exhaust easier)
Torque wrench (3/8" and 1/4" both good to have)
Floor jack and safety stands (or ramps): basically some method to raise front, if you need to take underpanel off, which you may need to, both for access and to recover dropped items.

 

I agree with the very first thing Jimbo said, about doing the maintenance in the manual. I agree with the comment about pre-emptively replacing the 12-volt battery if it's 6+ years old, simply because it's one of the few failures that can strand the car. I wouldn't pre-emptively spend a thousand dollars on an EGR system that hasn't failed, although I would probably spend $20 plus $80 labor to pop in a new PCV valve to proactively maintain it. Other than that, I mostly agree with bettergolf. You've read scary things on this site because the posters on this site write each other a lot of scary things. Statistically, however, your car is extremely dependable and you should do your standard due diligence and then just drive it.

 

What Tony said.

On the EGR business, if you're looking for a middle ground between "out of sight, out of mind, I hope" and "hours of knucklebusting to visually check/clean EGR in case there might be a problem", there has been the start on whether there might be a practical non-invasive way to find out how clogged that system might or might not be.

The best data point gathered so far (so this is still all very preliminary, or I wouldn't be saying funny stuff like "the best (solitary) data point") comes from jas8908, who measured both before and after cleaning the EGR, and did see a significant change in how far the valve can be opened before the exhaust starts to suffocate the engine. The number went down, as you would expect after cleaning.

So that might end up offering us a quick, no-knucklebusting way to judge whether the EGR condition should be an urgent concern, a modest concern, or not much concern, on a particular Prius.

 

Statistically, you are at the far end of the so called “ Bathtub curve” for reliability. At over 200K, you would be at a higher than normal probability of a failure of some sort. You just have to take your chances, I guess.

 

Just drive it but check the oil dipstick every morning before starting out. Have a good trip.
P.S. Check the spare tire air pressure before leaving.

 

The miles are getting up there, all right. But I agree with those who say that, it's well maintained, you should be fine. Your most likely major repair, even now, is probably from getting rear ended.

 

I think I spent about $4.50, for a can of brake cleaner. And borrowed a few scoops of Oxi-Clean from the laundry room. I gave the pcv valve a shot of carb cleaner while I was in there.

No offense, but the intake and egr systems are not good/fail items. They slowly but inexorably clog with carbon, and your combustion chamber temps climb as the clogging progresses. By 200K miles they are well along.

 

In my 2010, the way that I found that my first two 12V batteries were weak was when I returned to the car and it was completely dead. No lights, no door remote, no nothing. Both times. And it had started and ran fine right up to that moment.

The first time I used the Optima Batteries 8171-767 (DS46B24R) YellowTop Prius Battery. But that did not last as long as the OEM battery by a couple years. So my current battery is an OEM Toyota battery I bought at the dealer.

 

That battery is usually hard to beat.

 

If you don't want to preemptively replace the 12V battery, I suggest carrying a compact rechargeable jump starter. You charge it just like you would a smart phone and then carry it in your glove compartment. You can get one from Amazon for about $70.

 

Fainting, when you see the gas prices in CA.

 

I really doubt anything bad will happened. As long as you have maintained your car throughout its life then there’s no need to worry. I took my Prius from LA to Bullhead City Arizona and it went well. No problems.