Maintenance necessary at 100,000 miles; coolant; tranny; brake fluid specifically

Are you the original owner? Do you have the Toyota USA's Warranty and Maintenance Booklet, say in the glove box? If no, a pdf can be dowloaded; "Toyota Tech Info" site is one source. Google that, and look in the "manuals" tab.

Here's a screen-grab from that booklet, what Toyota USA says to do, at 100K:



It's basically an oil and filter change, visual inspection of the brakes (trivial), possible cabin air filter replacement (would only do if it needs it), tire rotation, and engine coolant change. Yeah I know, it says inverter coolant too, but if you follow footnote "3" you get to this, pretty much contradictory, and governing statement:


This booklet is in an event-by-event format, which has it's pros-and-cons. A big con: it's impossible to see the patterns, the frequencies of the various services. Accordingly, I cobbled a spreadsheet format summary (attached).

Regarding possible extras:

1. Brake Fluid Change: Toyota USA says nothing about changing brake fluid. FWIW, Toyota Canada says to change it every 3 years or 48K kms (whichever comes first). A gulf of difference there. With your miles it would be worthwhile, but your call.

I've DIY'd this a couple of tiimes, using the non-Techstream method (outlined in the Repair Manual, excerpt attached). I put the whole car on safety stands, and took off the wheels. This is not techincally necessary, but makes the brake bleed bolts a lot more accesible. With my wife helping, pushing the brake pedal, using a few wrenches, some tubing, and a largish plastic jar to catch the drained fluid, I used two pint bottles of Toyota DOT3 fluid (cost about $15 in tota)I accomplished this in about an hour (not counting the time to raise/lower car, remove/install wheels).

I appreciate you're not a DIY'r, but I'm just trying to paiint a picture: this is NOT complicated. If the dealership does it, it should NOT much over $100, or you're being ripped off.

2. Transaxle Fluid Change: Again, just crickets from Toyota USA. Ditto from Toyota Canada this time. But yeah, definitely do it. Ideal would be around 1 year or 10K miles, believe it or not. But anyway: VERY simple procedure, similar to an oil change in difficulty. Repair Manual excerpt attached, just FYI. If dealership does it, should NOT be much over $80~90, or...

3. EGR (Exhaust Gas Recirculation) System Cleaning: 100K is a very opportune time to get on this. This is a new pollution control system with gen 3, that also aids fuel efficiency. The big problem though, is the new design slow-but-sure clogs with carbon, and leads to head gasket failure.

The dealership will very likely be the last place you want this done. They will tell you it's not necessary without codes/symptoms (by which time it's typically too late), and that the only way to go is replace parts. The parts replacement alone will run over a grand, without labour.

I would suggest you start by reading through the first link in my signature. If DIY is completely out of the picture, I'd look for an independent mechanic who's knowledgable about this, or a fast learner.

 

The Prius is not a car that you want to just leave without use for months. Nickel metal hydride batteries do not like to sit for long periods of time. This is not really an issue with lithium batteries. A Prius with 150k miles could have a stronger battery pack than one with 100k if it was used more consistently. I know there are ways to store the Prius for long periods of time but I would honestly sell your car in this hot market and get a used Corolla or civic that’s easier to store for longer periods of time like 6 months in your case. This is just my opinion, but the 3rd gen Prius is loaded with issues beyond replacing fluids.

 

Good point. Owner's Manual says this:



For the 12 volt battery, steady connection to a smart charger (3~4 Amp rating) will protect it, or at the least disconnect and isolate the negative cable.

Sitting for 6 months the tires may start to develop flat spots. Airing them up to max sidewall will help prevent this. Also good to have full gas tank, fresh oil change.

 

Engine coolant change IS scheduled for 100K in the States, not an extra. FWIW, in Canada, the recommendation from toyota is to do inverter coolant also, at 100K.

An EGR "problem" is more-or-less inevitable. The system reliably clogs up with carbon. Somewhere between 150K and 200K, as the head gasket lets go, it moves on to cold-start shakes, coolant loss, and if ignored long enough: a hole in the block. 100K is the latest you want to leave this, if you plan on keeping the car.

This might trump all the possible issues.