E3 spark plugs

I have never been impressed with those E3 plugs, also I have not seen any real change with them installed. I wouldn't waste the money.

 

I would stick with stock spark plugs. If you really want to save fuel and get the most performance form a single bang then get the most expensive ones Toyota recommends for your vehicle.

 

The stock plugs are the best made and best functioning spark plugs, in my experience. They are used by racers as well (obviously in different heat ranges and different sizes in various engines).
This is why they don't need to be changed until you go 60,000 mi (100,000 km). The downside of leaving them in that long is they can corrode in place and be very difficult to remove. I advise loosening and re-tightening them every 20,000 mi (35,000 km). Do be careful though. You should know how to avoid damaging them or the block. If you are worried about your skills in this area, get a Toyota mechanic to check them for you.

 

We stayed with stock plugs too.

 

No real payback (performance or FE) with exotic plugs. Just use standard spec ones.

 

Don't bother, stick to stock or comparable iridium. Was worried about my plugs getting seized so at 39,000 had them swapped. Don't know if they were defective or if they were improperly installed, but car began to misfire on 4th cylinder. So after $85 tow and dealership charging me $75 to reinstall original plugs, I regret ever having them swapped. Should have listened to that old saying that if it is not broken, do not fix it!

 

I couldn't resist posting how your comment on the "old saying" was one I often used on my deceased father who loved to tinker on cars...even when they ran perfectly. After his last biggy on a fuel injection system that he knew nothing about he spent several hundred dollars to repair his "improvements"
At least his heart was in the right place

 

I use NGK BR9EIX plugs in my Gen II Prius. They've been working great. No issues yet.

 

Don't forget to use antiseize on threads. Since the engine has an aluminum head this is necessary.

 

Everything I have ever read about these plugs on/in any forum/mag, tells me to stay away from them. a new E3 in comparison to one that has a few miles on it is like night and day

 

Right.
If they really made any worthwhile improvement in performance or economy I am confident Toyota and other manufacturers would snap them up to raise their EPA figures as well as test track numbers.

 

I use Denso ik16's this type of Iridium plug are used as standard on the later gen 3s though probably a different number.