Best spark plugs?

none. best to use the recommended oems

 

"I own a geo metro and noticed that copper plugs work best"
And how do you KNOW it's the plugs in your Geo Metro. Have you compared yours to other Geo Metros with OEM plugs? And how do you KNOW it's not some other factor, or even if it's a change in your driving methods, or whether a Prius will behave differently than your Metro (which ain't a hybrid...). I could go on....

 

BINGO.
Over the years there has been a LOT of marketing hype (lies) about all kinds of different plug electrode configurations........
and they all just MAKE A SPARK.
Independent tests have generally shown:
Replacing OLD plugs with most anything new will be an improvement.
Replacing "conventional" plugs in good condition with any other configuration of electrodes does.......nothing useful.

 

I think that hype is dying out, especially with the advent of spark plugs that have such long service intervals. You don't mess with success, just replace with the same.

That said, the official 3rd gen plug spec has been revised I think, to a slightly hotter plug. Owner's Manual for our 2010 says:

Denso SC20HR11

But I believe now, if you check with dealership parts department, it'll be:

Denso SC16HR11

 

I can't see why the electrode material would make any difference to the mpg, but it could certainly make a difference to the longevity of the plugs.
Is there any difference in the configuration of the electrodes in different kinds of plugs? (What happened to those plugs with triple ground electrodes that I recall from way back?) I can see that that might affect the efficiency of combustion and therefore the mpg.

 

Somehow that reminds me of disposable razors with 4~5 blades.

 

no

 

On NGK site they probably have a compatibility chart. Or plug in your vehicle and it shows compatible plugs.

Had a look:

This (CDN) page you enter your vehicle:

PartCat

And when I enter 2010 Toyota Prius, it shows:

NGK Laser ILKAR7B11

It would more'n likely be comparable to the stock plug, no better or worse.

FWIW, our previous 06 Civic Hybrid had two plugs per cylinder, and when I pulled them: each cylinder had one Denso and one NGK.

 

Copper spark plugs used to be what everyone used.

Then as the rest of the car became more reliable, Platinum spark plugs were introduced that amazingly and dramatically increased replacement intervals to 100k+ miles. Of course, many marketing claims of power/mpg/etc. but the main truth was longevity. This then further advanced evolution to the point where designing the car with convenient access to spark plugs is sometimes an afterthought, as we have in the Prius. I have replaced Platinum spark plugs at 100k+ miles that looked and measured as new, which I find amazing, vs. the ablation/erosion which used to be common on copper plugs after 30k miles.

Platinum vs. Iridium vs. Ruthenium all tout new technological capability, but it may be more related to the relative pricing of those 3 metals. When one spikes, they move on to the next. They may be close to functionally equivalent.

Another major true factor is "double" platinum or whatever. This is where there is a second spot of the precious metal on the ground electrode. So both anode and cathode will be made of platinum or whatever, and will last virtually forever. With "single" platinum, even if the platinum electrode does not wear, the ground electrode will erode, leading to an increase in gap, and less consistency in spark, possibly ignition issues.

But THE BIGGEST FACTOR in choosing spark plugs in 2019 and beyond is to make sure they are not FAKE. I've seen some shocking photos of even dealer-sourced fake plugs. I do believe that the "double" ones are a little less likely to be faked (more work), and more likely to be real. Next time I need to buy plugs, I may use that as my purchase decision driver.

And if your car is running fine right now with the plugs you have in there, I would save them for future debugging purposes if needed.

 

And that means that the center electrode body inside the plug is maintained at a slightly higher temperature.
That should help prevent carbon buildup on the electrode itself.
It should have little to NO impact on the spark efficiency.

 

^ agreed fake plugs are a problem, especially with ebay and amazon.

 

Memories from the Good Old Days!
Ok, some aviation ICE spark plugs had triple ground electrodes surrounding the center electrode so that if one or even two of those gaps carbon fouled, you would still get s spark across the remaining gap. However, the triple-electrode plugs I had were larger than a standard automobile spark plug thread size and would not fit any automobile except the 3 -cylinder, 2-stroke engine of my (1959?) SAAB 93b. That was a godsend because after my brother rebuilt the engine, one of the crankshaft seals between the cylinders was faulty, and the result was that one cylinder ran rich, another cylinder ran lean, and the final cylinder ran normally. So I had to use a triple gap aviation spark plug in the rich mixture cylinder, a colder than normal range spark plug in the lean burning cylinder, and a normal plug in the normally operating cylinder. Thank dog the plugs were easy to access as I was removing and cleaning them constantly during my ownership of that vehicle. [That was also the only vehicle I am aware of where it was possible to start the car and run over your own foot at the same time, but that’s another (very embarrassing) story.]

 

Very true. Beware: The next bargain spark plugs you buy online might be fakes | Get the latest car news, car reviews, auto show updates, and racing news from Autoweek. News for the auto enthusiast.

 

Something is wrong with that picture.
Carbon fouling produces a SHORT between the two electrodes.
Even if it is not a complete short, the resistance would be a LOT lower than the non-fouled gap and would sap off ALL of the spark.

 

Thanks for the heads up on fakes. So, to protect yourself against fakes, you should purchase in a local store (Walmart, AutoZone, PepBoys, etc..)?

 

I love buying stuff online. But having been burnt by this before, yeah. I usually go to the local NAPA or Advance for this item.

 

I don't know if buying at an actual store guarantees genuine plugs. I saw somewhere on a forum I read recently where plugs bought from the DEALER were fake. Platinum/Iridium plugs that had eroded away after ~20k+ miles since those precious metals were apparently substituted for Chinesium or some other less durable metal.

So whatever you get, learn what to look for and inspect. The link in post #15 had some interesting info and youtube video. But even there, there are inconsistencies.

I think the game plan of the fakers is to sell a plug that will work for 20k miles, and price it with the ones for 100k miles. So it can't be too horrible. Looking at the youtube video in post #15's link, the main difference I noticed (which the youtube guy mostly skipped over) is that the actual electrode was physically wider on the (supposed) fake one. It makes sense to me that the Platinum one would be able to be thinner, but a cheap fake would need to be fatter if it tried to function. The other significant difference in that video was the boxes were different, the supposed fake one claiming "double platinum" on the box, whereas the one in there was clearly not, not even trying to fake it.

The double platinum would mean that there is a landing patch of platinum (or iridium or ruthenium) on the underside of the ground electrode. "Double" means not just the center electrode (single) but also the ground electrode (second one = double) has the precious metal on it. It makes sense to me that faking those will be tougher, and why do the tough things when you can do the easier ones?

Next time I buy plugs, I'll try to get the double platinum as step one, and will carefully inspect. And as I often do, I'll buy from RockAuto.com. They are online of course, very price competitive, but unlike Amazon, all they do is auto parts, and I expect they are smart, careful, and powerful enough to not get ripped off by the fakers. Amazon is happy to pretend they don't know any better and refund the few knowledgeable consumers who call them on it.

 

I have a local automotive specialty store that's been very dependable for spark plugs. Always at least 25% cheaper than dealership.