Best Spark Plug Replacement for Gen4?

When you get to 120,000 miles or 10 years, you want Iridium plugs

https://www.toyota.com/t3Portal/document/om-s/OM47B39U/pdf/OM47B39U.pdf

Page 732 DENSO FC16HR-C9

A local NAPA may have them

https://www.napaonline.com/en/p/DEO3514

 

Are the Owner's Manual spec'd. plugs still hard to find though? Maybe new plug for 4th gen, and not too many owners looking as yet, not enough demand?



Just according to this website:

Genuine Auto Parts Store| Auto Parts Direct Singapore

Toyota part no for above:

90919-01281

McGeorge Toyota concurs:

Spark Plug - Toyota (90919-01281) | Toyota Parts

(Sorry about the runaway font)

 

Handbook says to use only iridium plugs.

 

These.... or the Autolite at Amazon are cheaper and they're double iridium.

More Information for DENSO 3499

 

I suspect nobody knows (or wants to experiment!!) - I doubt if any Gen 4 have got to 200,000km (as mentioned by JimboPalmer).

I'd consider putting genuine in if the price is reasonable - I'd assume TOYOTA tested something like that carefully as they wouldn't want them to fail before the 200,000km.

 

They may be purchasing soldierguy's old car. I doubt many 2016 Prius in California have over 90K miles already.

 

I just verified the 2017 uses those same plugs so the 2016 should use them too.

 

2016 Prius manuals are here.

2016 Toyota Prius Owners Manual and Warranty - Toyota Owners

 

Genuine is the aforementioned Denso. Toyota does assign it a Toyo part number, but it's a Denso plug, just like tires.

 

I was referring to the user here who started this thread. He traded in his Prius with over 90K miles for a VW Diesel.

Super-Commuter & high mile thread | PriusChat

 

Yes appears Iridium plugs.
Many brand choices, yet staying with OEM insures correct reach and heat range.
Iridium is good for 100K mileage, wear would show with a gap measurement.
Your plan to change at 100K is perfect IMO.

FWIW copper conducts electricity better than exotic metals.
But then you need to change plugs ever 25K mileage.
I would replace with OEM plugs and call it a day.

Good luck with your decision.

 

I replaced my original plugs at 140,000 with Denso Iridium. At 180,000 I started getting a missfire at idle, after checking, I found that the plugs had fifty to fifty five thousandth gap and there was no iridium tip on the ground electrode. I didn't have a way to the parts store, so I reinstalled the original plugs and still working fine. The gap on the original plugs is still good so I'll get around to replacing the originals if they start missing.

 

It says somewhere not to adjust the gap - which is contrary to anything we've done over the past 100+ years, but they seem to work fine that way. Which is a good reason to buy OEM, as you'll be guaranteed (hopefully) they're to specification in the first place.

 

Yes, a fair amount of the necessary advice on Prius chat is 'Don't do it like it was 1968, do it like it is 2018"
Iridium must not be very malleable.
Wikipedia says "Iridium is a chemical element with symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, iridium is the second densest element (after osmium). It is also the most corrosion-resistant metal, even at temperatures as high as 2000 °C.

Resisting corrosion sounds good but brittle is going to rule out gapping the plugs.

 

I don't have facts but I think just the very tip has the iridium on it, the part you always bent is the same.

 

Bosch's website says "Iridium spark plugs can reduce voltage demands by 24%, leading to a longer spark plug life." I can't see where they first started being used, with Platinum preceding them, but it seems aviation were the first users.