NGK Laser Iridium vs Bosch Double Iridium spark plugs

They are both reputable manufacturers, I'd buy based on price. When an engine gets older I don't expect, nor want to wait another 100K mi to check the plugs and while they're out doing that, replace anyway.

What model year, how many miles on the engine? To me it seems kind of foolish to spend a premium on a vehicle that may not have a lot of value, particularly when the premium is spent on knee jerk reactions and internet fables. Past a certain age or mileage, double iridium seems like a waste of money even at $9/plug.

At the same time, we're only talking about a cost difference similar to the price of a lunch or two. If it helps you sleep better at night, that's worth something. ;)
 
@2010Civic & @tyman
Thanks for your input!

@Dave9
It's a model of 2010 with about 125.000 miles. The engine is in perfect condition.

I have also a question: Do these iridium plugs truly last for 80-120 thousands miles as their manufacturers claim maintaining full performance or does their performance has started to drop earlier from the suggested point of change?
 
Japanese & Korean get NGK, Denso
German & other European get Bosch, Beru or Hella. APR and Brisk spark plugs are gaining too ground in EU markets
American get Autolite, (Ford) Motorcraft or (GM) ACDelco

Or to make it short, get the same brand what spark plug installed in the car.
 
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Japanese & Korean get NGK, Denso
German & other European get Bosch, Beru or Hella. APR and Brisk spark plugs are gaining too ground in EU markets
American get Autolite, (Ford) Motorcraft or (GM) ACDelco

Or to make it short, get the same brand what spark plug installed the car.
Lots of europeans are running NGK from the factory these days, especially the high performance stuff. And watch for some engines only allowing one particular plug - the very highly strung Fiat 1.4 multi air (in Fiat and Alfa Romeo and Dodge Dart etc) will only tend to run properly on the NGK Fiat contracted NGK to make for them specifically for this engine.

And its easy to assume "because marketing" like it is with oils, but these engines usually (but not always....) develop misfire issues on the Denso equivalent etc.
 
I have run the NGK Iridium now in 2 vehicles for 100K stints now I think 4 times if I have my math right, almost at 5. I have never had a plug issue, and they always came out looking great. Sold me on them. They are factory spec'd in mine and the service interval is 105K per the OEM.

As for whether they will last 100K in your vehicle - follow the service interval in the manual. The coils and spark voltage have as much to do on how long they will last as the plugs do, so I wouldn't deviate from factory spec - although many do.

Not tried the Bosch so no comment on those.

As for using lower dollar plugs in older vehicles to me is counterintuitive. Last thing I want is a mis-fire mile enough to not throw a code, but often enough to foul a cat.
 
Fiat Powertrain spec an NGK Iridium plug in the 1.4 Multiair turbo in my Alfa Romeo - with a recommended interval of 30,000kms.

Yep - 30,000kms (not miles) from Iridium plugs! These engines are pushed pretty hard!
 
I’m biased towards Japanese plugs - but it looks like Bosch ditched their old “recessed” design and went with what everyone else did. Made in Germany, I would have no qualms using those if the OE plug isn’t available and there isn’t a need for special plugs(Toyota D4-S Denso tri-electrode, Mercedes indexed Bosch plugs, Ford 3V).
 
Japanese & Korean get NGK, Denso
German & other European get Bosch, Beru or Hella. APR and Brisk spark plugs are gaining too ground in EU markets
American get Autolite, (Ford) Motorcraft or (GM) ACDelco

Or to make it short, get the same brand what spark plug installed in the car.
Bosch was so good on VWAG engines, that they ditched Bosch and went to NGK as their supplier for spark plugs
 
I have run the NGK Iridium now in 2 vehicles for 100K stints now I think 4 times if I have my math right, almost at 5. I have never had a plug issue, and they always came out looking great. Sold me on them. They are factory spec'd in mine and the service interval is 105K per the OEM.

As for whether they will last 100K in your vehicle - follow the service interval in the manual. The coils and spark voltage have as much to do on how long they will last as the plugs do, so I wouldn't deviate from factory spec - although many do.

Not tried the Bosch so no comment on those.

As for using lower dollar plugs in older vehicles to me is counterintuitive. Last thing I want is a mis-fire mile enough to not throw a code, but often enough to foul a cat.
  1. Does the looks always mean also great performance? Or is it possible for a spark plug that looks good to produce a weaker spark compared to its original specs?
  2. Should the car's manual be followed first, before the recommendation of the spark plugs manufacturer regarding the service intervals?
 
  1. Does the looks always mean also great performance? Or is it possible for a spark plug that looks good to produce a weaker spark compared to its original specs?
  2. Should the car's manual be followed first, before the recommendation of the spark plugs manufacturer regarding the service intervals?
I am sure color is not perfect, but if there running too hot the electrode will get burnt up and rough. If there running cold they will look fouled. If the electrode is clean and smooth and the ceramic is tan, its pretty clear indicator that the plug is firing correctly.

And yes, I would follow the manufacturers recommendation on duration. The spark plug manufacturers rating is simply their theoretical max for the plug. The OEM should take into account any special operating conditions. You can always try to run longer - say yours came with platinum and you switch to Iridium, in theory you could run them longer, but of course the issue is you don't really know how they all look until you pull them. I suppose in that case its your call.
 
Either these or those.
1669254513518.png
 
I am sure color is not perfect, but if there running too hot the electrode will get burnt up and rough. If there running cold they will look fouled. If the electrode is clean and smooth and the ceramic is tan, its pretty clear indicator that the plug is firing correctly.

And yes, I would follow the manufacturers recommendation on duration. The spark plug manufacturers rating is simply their theoretical max for the plug. The OEM should take into account any special operating conditions. You can always try to run longer - say yours came with platinum and you switch to Iridium, in theory you could run them longer, but of course the issue is you don't really know how they all look until you pull them. I suppose in that case its your call.

I have heard otherwise. That even if a spark plug looks OK to the naked eye as it ages, as more miles get added to it, its performance drops and the spark it produces gets weaker.

I don't know if that perspective holds any truth though.



I'm currently using Densos. No issues personally, but I was speaking with a car mechanic who told me that the last 1 - 1,5 years he sees Densos that their ceramic has cracked, so I'm having second thoughts about reusing them. That's why I'm asking for opinions about NGK and Bosch spark plugs.
 
Long ago when I worked for VW we used Bosch Super plugs most of the time. They worked well but occasionally the parts department would buy Beru plugs. I thought they were better than the Bosch. They are made in Germany and aren't common in the US. If you are you are located in Europe you could get a set and try them.

1669305594413.jpg
 
Just checked the car's manual. The 4A91 originally had Bosch FR 7 SI 30 Iridium spark plugs and the suggested interval for change is 90,000 km (56,000 miles).
 
Any opinions about these 2 spark plugs:
They are going to get installed in a Mitsubishi Lancer 4A91 engine that has been converted to LPG.

The price of the Bosch ones is about $9.30 per plug and NGKs are priced at $15 per plug.

Is there really any difference in their quality regarding their performance or their lifespan?
I have a set of 4 Bosch IR at home purchased from a big autoparts store near me for a Subaru EJ I sold before the install. They look like fantastic quality. They are OE on BMW turbo V8 7 series and other European cars. I don't know the part number off hand. Just collecting dust.
I see you are located in Greece, otherwise I'd sell the set to you for 20 bucks plus postage.

I have BOSCH p/n: 9604 if anyone is interested. I can photograph and post the business end for your perusal.

- Ken
 
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Fiat Powertrain spec an NGK Iridium plug in the 1.4 Multiair turbo in my Alfa Romeo - with a recommended interval of 30,000kms.

Yep - 30,000kms (not miles) from Iridium plugs! These engines are pushed pretty hard!
LZKR6AI-10G is used in my lpg car.
I think same interval.
 
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