Spark plug lifespans and choosing best plugs

[CharlesInCharge]

On a rarely driven vehicle, say 1000 miles annually, what's smarter?

Manual states as follows:
Conventional plugs, change every 24k miles or 2 years. These are $1.50 to $2 each.
Platinum or iridium, change every 120k miles or 8 years. These are $6-8 each.

The plug job on this vehicle is very easy. 10 minutes per plug. But minor risk of breaking small plastic clips or separating the coilpack boots, which are $50 each. Regardless, I may want to do regular plug inspections so digging in there may be needed regardless.

I cannot come close to the miles. So plugs are replaced on a time schedule.
Are fresh conventional plugs every 2 years (2000 miles), smarter than letting platinum or iridium plugs last 8 years (8000 miles)?

Or do you have a different opinion other than "drive the vehicle more?"

 

[Chris142]

Stay away from Autolite platinum and double platinums.

 

[ripcord]

What!? Why would one change 2 year old spark plugs with only 2000 miles on them? Just go by mileage.

 

[kschachn]

What!? Why would one change 2 year old spark plugs with only 2000 miles on them? Just go by mileage.

Exactly. Don’t the spark plug manufacturers publish a mileage statement for the different types? Just follow that. It’s not rocket science.

 

[CharlesInCharge]

What!? Why would one change 2 year old spark plugs with only 2000 miles on them? Just go by mileage.

This is a good point. Certainly already considered.

Counterpoint, "the manual" states X miles or X years, whichever presumably is first.

24k miles would be over 24 years, which would probably far exceed by many multiples the designed lifespan of any spark plug.

 

[circuitsmith]

I would use conventional plugs and change every 10 years.
The mfr recommendation isn't optimum for this outlier case.

 

[2EHA]

indefinite lifespan

leave them alone

 

[ripcord]

I don't know of any spark manufacturer that rates spark plugs by time in service, only by mileage. Spark plugs are not like eggs and butter

 

[Lubener]

Go conventional and mark your calendar to change them in 24 years. The 2 year interval in nonsense.

 

[Warstud]

If your not experiencing any spark plug related issues.....don't change them.

 

[NitroM3]

Spark Plugs used in aircraft are by hours. Spark plugs in a engine are cheap and if you want the best overall performance in power and MPG then you should change them waaaaaaaaaaaaaay more often then any recommendation from advertised spark plug manufacture or even the auto manufacture.

You bring you vehicle to me with more then 10k on any spark plug and I will show you a less then great wave form on your ignition from your spark plugs! An ossicscope dont lie. !

Want to quick experiment take you vehicle with your unchanged 10k sparkplugs have someone follow you and film what happens when you do a short full throttle burst. Then change the spark plugs and do the same thing. Then come back to this thread and tell me about those 10k plus spark plugs you all think should be ok for another 10-20-30 k miles? LOL

 

[NitroM3]

If your not experiencing any spark plug related issues.....don't change them.

Really if that's your good looking Chevelle in your signature I bet you change your plugs often LOL
So why would you ever post what you did. Most people would not know if there was a problem until it was a DTC, poor throttle response lower MPG etc. They just keep on trucking until the problem is so apparent. Then the shop show them there spark plugs as the problem LOL

 

[Mainia]

Turbo cars with high boost/high heat "highly sport driven" 25,000/30,000 miles is the time to change them out. Hyundai recommends 42,000 on their "stock" turbo motors. After that they were finding too many dropped/cracked porcelain insulators and grounding electrodes. This lead to too many damages warranty engines for them. Stock and proprietary OEM NGK and/or Denso's are around $22 each. My HKS race plugs are $30 each.

 

[NitroM3]

Turbo cars with high boost/high heat "highly sport driven" 25,000/30,000 miles is the time to change them out.

I think you might have miss typed...truly "highly sport driven" any engine 2,500/3,000 miles is the time to change them out.

 

[Hall]

What type of plugs are in it now, conventional or Iridium ? If it has Iridium in it, driving 1000 miles a year, you'll never have to change them.

 

[NitroM3]

What type of plugs are in it now, conventional or Iridium ? If it has Iridium in it, driving 1000 miles a year, you'll never have to change them.

This is not exactly accurate at all. How did you "guess" this? You realize that spark plugs need to have the engine operate at the optimum temperatures in the combustion chambers so that they will clean and not have by-product of unburned and incomplete combustion start to degrade their performance.
Also what ever made conventional (POOR DISCRIPTIVE TERM) spark plug less effective in some operating perimeters as what you described would be , what the opposite "unconventional spark plugs? LOL

Sorry but really ignition system in vehicles has always interested me when I got to see my first wave form and the use of variable magnetic ignition coils. work. On my performance engine I chart out what spark plug type heat range and most effective gap based on use and DYNO results and power and pull spark plug readings. I also live by diagnosis my vehicles and hundreds of customers ignition issues use an oscilloscope and watching what the ignition system is doing . I would guess at least 80% of the time it is spark plug related and most all the spark plug issues the spark plugs had a record change of between 10-30k miles and every type of spark plug. NONE last as you all think! I wonder how many of you have tested your spark plugs with a digital volt ohm gauge before installing them? You know how many variables there are in a 8 pack. At times I have had to buy several packs to find 4 that I would use.
So come on with no reasonable explanation where you came up with your response ? The word ASSUMPTION comes to mind?

Spark Plugs are cheap most applications easy to change and will insure the support of the best performance you can achieve from your engine.

 

[Warstud]

Really if that's your good looking Chevelle in your signature I bet you change your plugs often LOL
So why would you ever post what you did. Most people would not know if there was a problem until it was a DTC, poor throttle response lower MPG etc. They just keep on trucking until the problem is so apparent. Then the shop show them there spark plugs as the problem LOL

I have about 350K (not a typo) on the plugs I have in my SUV. Starts great...runs great....mpg great. No need to change them. imo
If you run them this long you should break them loose once in a while so they dont get permanetly stuck.

 

[Mainia]

I think you might have miss typed...truly "highly sport driven" any engine 2,500/3,000 miles is the time to change them out.

Yes, thank you. Highly sport driven (autocross in non pedestrian areas, IE parking lots, country roads and on ramps. 25,000/30,000 or less actually, with high boosted turbos in the 25 to 30+ psi boost points.

 

[NitroM3]

I forgot there is always that one forum member not only this forum but everyone I have ever been on that is the exception to normal parts wear and use of things and the physical known universe we all share and live in. ROLMAO......... 350k miles on one set of spark plugs and no depreciation of engine performance ...someone quick call Guinness World Records all the spark plug manufactures we have a one for the record books! LOL

 

[CharlesInCharge]

I have about 350K (not a typo) on the plugs I have in my SUV. Starts great...runs great....mpg great. No need to change them. imo
If you run them this long you should break them loose once in a while so they dont get permanetly stuck.

Why would you experiment this way? Big gamble. Probably at least 3-5 times or more the recommended miles service interval. Plugs are almost free, and the labor is generally minor. Even a shop might charge only a couple hundos.