Spark Plug Hubbub


Is there really any significant difference between the $1 spark plugs and the $4 ones that my local parts store offers? I’m changing them today and wonder which ones to go with. Thanks.



Year, make, model would help…


The cheap ones are copper and the pricey ones are platinum or iridium. Both will work about the same, the latter will last longer.


I’d like to add that some makes and models don’t like certain spark plugs. A lot of Mitsubishi V6’s don’t like platinums, especially Bosch. Most Japanese cars don’t like Autolites. Even though these plugs were spec-ed to meet the requirements of the engines, there was a very noticeable performance drop while using them. It was corrected by changing to the plugs offered by the manufacturer.


Well, the platnum and iridium ones will function longer than the copper ones, but the general concensus seems to be that, though the platnum and iridium plugs can last for 100k+ miles, it’s not really a good idea to leave them in that long because they can become very difficult to remove. A copper plug should have no problem functioning through a reasonable change interval.

As for performance claims some of them make, the spark plug more or less just needs to carry a spark, which on a stock ignition system any plug that meets the manufacturer’s recommended specs will do just fine.


That seems to be typically true for as long as I can remember. Normally it is best to use the same brand and heat rating that was in your vehicle when new. I don’t know why this is so but would like to.


I generally agree with what has been said, but I would say there are three kinds of plugs. Standard exotic metals and designer.

You car came with and recommends one of the first types. Stick with what it came with from the factory. It is also true that cars seem to like the brand that it came with from the factory.

Never bother with the designer plugs with 16 conductors power turbos and diamond tips.


That question is a no-brainer.

Like a couple of these posters said: use what the engine/auto manufacturer recommends.

Unless you need the best for a very high performance engine (ie. race car), you’re just wasting your money.