What "Recommended Maintenance" should really be done?

What’s the history maintenance? Spark plugs are changed at 120,000 mi, if they weren’t then it needs to be done. If it was changed at 120,000 then you don’t need it. And if brakes were flushed last month, you don’t need it. Catch my drift

 

I'm stumped by EFI/AIS. EFI is maybe Electronic Fuel Injection, AIS: no clue.

When in doubt, go back to basics: read the Warranty and Maintenance Booklet, stick with that for now?

 

welcome!
follow the maintenance schedule that came with your car. add egr circuit cleaning and tranny fluid change.

 

I don’t know what an EFI/AIS is, so you don’t need it.

The spark plugs for $155 is a good deal, especially if they use the Toyota-required iridium spark plugs. Spark plug change on a Prius is quite labor intensive.

Your engine coolant and inverter coolant (separate things) should have been replaced by now.

It would be good if they inspect the brakes, which probably need mo work, and lubricate the brake sliding pins, which is very little work.

A transmission oil change in a Prius should cost no more than $150, and I’m being generous. Do not fall for any stories about “transmission flush” or “torque converter.” The Prius does not have a torque converter and there are no transmission lines to flush. So if they tell you transmission fluid change will cost $300, don’t let them do that. I had a dealer try that. I’m well-informed and everybody here will back this up: Transmission flush is impossible on a Prius; you just unscrew a bolt, the fluid comes out. You put the bolt back (with a new gasket) and put the new fluid in. No filter, no flush. So it’s inexpensive.

 

Yes, more like no more than $100. Four quarts (or liters) of Toyota ATF WS and fill/drain bolt replacement washers retail for around $40, and it's a simple drain and fill.

A scenario: you have a brain bubble, and pour motor oil into the transaxle. Now what?

Honda has a guidance for flushing a transmission: drain and fill (with proper fluid), then drive around the block. Repeat twice more. And this is for a regular automatic transmission, one where you maybe get 50% of the fluid out, with a single drain.

But yeah, if there's no contamination, then a "flush" is not needed. Still, the term "flush" is just ubiquitous, when talking about transmission fluid change. I seem to recall @NutzAboutBolts using the word, even when he was (obviously) just doing a drain and fill. Sometimes you just have to go with the flow, lol.