Are spark plugs all the same?

[ihookem]

I think I need new plugs in my 08 Impala. Some are $15 , some are $5. Has anyone noticed the expensive ones are better and last longer?

 

[theavgjoe]

They have different designs for better spark, whether that is true of not is up for debate. There is one important thing to remember is that they have different temp ranges which is what the single digit stands for on the model of plug. For instance a 5 is better for colder weather and a 6 is better for warmer weather or condition. I would stick with what whatever the OEM recommends and gap those plugs according to OEM. That is how the engine was engineered with trial and error, just my 2 cents.

 

[hoooogan]

Short answer: Just use OEM plugs. You have a better chance of losing performance if you switch away from the OEM iridium plugs.

 

[madtinker]

As was said, some plugs have hotter spark than others. The manufacturers would have selected a spark plug that results in optimal combustion for that particular engine. Older engines might benefit from experimenting with newer plugs, but unless you are seeing signs of combustion issues, OEM would be the way to go.

 

[Alpine4x4]

If you're stock and not modified just stick with the OE plug. The only time you should be straying away is if you are modifying and thus needing hotter or cooler plugs with different gappings.

 

[boom0906]

Replace them with the factory AC plugs

 

[StuckInTheEast]

short answer...put back in what the oem had in there from the factory for that application or whatever NGK that part number crosses to.

Slightly longer answer..They are certainly not all the same, especially on newer vehicles. Your application would likely be more generic/forgiving, but it's not worth the fuel/time expense to swap them out if you go cheap and have an issue and have to do it again in this instance.
Having done auto repair professionally my entire adult life Ive seen plenty of poor running engines come in with cheap, incorrect or improperly gapped or damaged Spark plugs being the cause.
Ive also seen a ton of people waste money replacing perfectly good Spark plugs because of misfire/poor running condition they didn't know how to diagnose and threw parts at hoping it was just spark plugs.
You just replacing plugs due to mileage/routine maintenance or having a problem your trying to correct?

 

[naked wombats]

Lots of counterfeit plugs on amazon/ebay these days too. Worth getting them from a real vendor.

 

[Bluefish]

Short answer, yes they are different. Heat ranges vary by manufacturer and new plugs are designed to last a lot longer than the old plugs due to emission laws. Even if the plug is a cross reference it might not be exactly the same. Even within NGK plugs there can be special electrodes for specific applications.

Btw $15 isn’t expensive for a plug. Used to run a $45 plug in a race bike back in the 90’s. Needed to be replaced every few runs.

 

[sndmn11]

Rock Auto is a gem

 

[ihookem]

short answer...put back in what the oem had in there from the factory for that application or whatever NGK that part number crosses to.

Slightly longer answer..They are certainly not all the same, especially on newer vehicles. Your application would likely be more generic/forgiving, but it's not worth the fuel/time expense to swap them out if you go cheap and have an issue and have to do it again in this instance.
Having done auto repair professionally my entire adult life Ive seen plenty of poor running engines come in with cheap, incorrect or improperly gapped or damaged Spark plugs being the cause.
Ive also seen a ton of people waste money replacing perfectly good Spark plugs because of misfire/poor running condition they didn't know how to diagnose and threw parts at hoping it was just spark plugs.
You just replacing plugs due to mileage/routine maintenance or having a problem your trying to correct?

Yes, the car has 119,000 on it . I bought it 4 yrs. ago with 45,000 on it so I am sure the plugs are original . The car does not idle at the saem RPM. The mechanic said it is best to just do the plugs anyway and I agreed. It is the 3.9 Chevy V6 and a bear to get the back plugs out. I hope it fixes the problem , but , like you mentioned , you have seen many people throw parts at the car and still not fixed. The check engine light went on a few weeks ago for 1 day and has not come back on since.

 

[Ope]

If it threw a check engine light it should have a code stored. If you don’t own a scanner, any auto parts store usually scans them for free. As most people suggested, I’d stick with OE plugs and with 119,000 miles I’d replace the plug wires as well.

 

[StuckInTheEast]

Yes, the car has 119,000 on it . I bought it 4 yrs. ago with 45,000 on it so I am sure the plugs are original . The car does not idle at the saem RPM. The mechanic said it is best to just do the plugs anyway and I agreed. It is the 3.9 Chevy V6 and a bear to get the back plugs out. I hope it fixes the problem , but , like you mentioned , you have seen many people throw parts at the car and still not fixed. The check engine light went on a few weeks ago for 1 day and has not come back on since.

Your due by mileage per oem recommendations for sure, but be good to know what the code was to know if it related to plugs or not. Anything with difficult to access spark plugs is certainly a good reason to go with oem parts to best try and avoid part quality issues and not introduce another problem in the course of trying to fix the initial issue you have.
And as stated, $15 a piece isnt high dollar on plugs these days. OE AC delco platinum or Iridium plugs likely in that range if your buying through repair shop.

 

[StuckInTheEast]

Rock Auto is a gem

They can be a real toss up but Its sad how often I have to go there to find parts no ones else local has or are on back order or discontinued from dealer and somehow RockAuto has them. Ive had some issues with getting junk from them a few times though.
Literally sent me a set of used parts a few times, most recently headgaskets for 8.1gm engine not long ago...like package taped up and gaskets all oily and obviously previously installed. Blind people managing returns department.
Few damaged parts as well. No worse track record than local stores, just bigger pain to return and virtually no chance of labor coverage for defective part.