First time preventative maintenance

No one mentioned it, but you've got to do quite a bit of disassembly (windshield cowl/tray under the wipers) before you can even get to the sparkplugs.

SM-G781V ?

 

You seemed to have missed the free and easier to use owners manual I pointed out.

No one has a factory repair manual other than pieces captured as pdfs from Toyota's TIS site.

 

see video 13 here:

Nutz About Bolts Prius Maintenance Videos | PriusChat

^ one quibble: he slathers plug threads with ant-sieze and advocates 20 ft lbs torque. Toyota Repair Manual says 15, and no mention of lube, so presumably clean/dry threads.

yeah, an astounding amount of disassemble required, just because the coils bump the wiper cowl underside an inch or two before they can be extracted. Not Toyotas finest engineering.

attached repair manual excerpt has spark plug info. Last page, with plug torque, is a thousand pages or so away from the rest.

Plug spec is shown in owners manual, except that spec has been superseded by Toyota, to a slightly hotter plug (“20” designation revised to “16”). I posted that updated Denso plug spec up the page, plus it’s Toyota part no (in post 14).

you’ll need a 14 mm (or 9/16”) socket. If it’s got rubber inset to grip plug, I’d recommend to tape socket to extension securely, to avoid it pulling off after new plug install.

 

I won't invest on anything but oil change first on the first 1 year/5k miles and check if everything is fine, the car does not burn oil, and everything works. After that:
1. Clean the EGR and intake manifolds, don't waste time too muchon trying to shining up the EGR cooler
2. Change the engine coolant with genuine Toyota SLLC if it has not been replaced before
3. Change the transmission fluid at the same time
4. Change the spark plugs at 240k miles
That's all, hopefully no problem before reaching no. 4.

 

One thing, the colloquial name "cooler" is not for naught: if it's purpose was solely to flow exhaust gasses, it wouldn't have the internal raidator. If that radiator has a patina of carbon, it may still have "sufficient" flow, but it's cooling ability is hampered. Several hour-long soaks with a concentrated solution of oxi-clean (or lye solution if oxi is inusufficent) can get it like-new clean, and restore it's cooling efficacy.

For expeidience when doing EGR cleaning, get the EGR cooler soaking started first, then go onto cleaning of the EGR valve, the pipe twixt EGR valve and intake manifold, the intake manifold (pay special attention to the EGR passages at each port), and the intake ports on the head. Maybe set an hour timer for rinse-and-repeat of the EGR cooler.

 

I soaked the EGR cooler in a brake cleaner solution by plugging both side holes. I have a used cooler for spare and reduced down time. I also have used intake manifolds and EGR valves. It costs less than $100 but can reduce the down time by hours.

 

I tried about 12 hours of brake cleaner soak, then gave up on that. A water-based, caustic cleaner (Oxi or lye solution) is much better.

 

That's true,I don't see much difference after soaking it with brake cleaner. It remove sludge and oily things well. I think hard carbon deposit best cleaner is always hot steam water+dish soap.