Sparkplugs change by age?

[guest4283]

Now that the colder weather is here I've noticed that Jazz isn't so willing as it was before.

I'm going to change the engine oil to 0W-30 soon, 'cause I'm sure dealer puts in 10W-40. But looking in Haynes manual it says that spark plugs should be changed the sooner of 2yrs or 24k miles. I believe mine is still on original plugs at 5yrs & 17k.

I can't find any information on the web explaining how length of service effects spark plug effectiveness. Is there some material used in the plugs that naturally degrades such that you'd have to swap them out after 2yrs even if you'd only done 10k miles?

[guest4283]

Just seen some Denso Spark Plug K20PR-U11 plugs for £1.33 each ! I was about to buy but then reality kicked in, best Amazon direct can do is £4.66/plug, so the £1.33 plugs are maybe Chinese knock offs!


Anyone had experience ordering from Mick's Garage?
http://www.amazon.co.uk/gp/product/B00ELM676E/ref=ox_sc_sfl_title_1?ie=UTF8&psc=1&smid=A1AFUX25AV3QVH

[guest255]

I don't do a lot of miles a year something like 7-8 k.

But I change my plugs every 2 years with NGK plugs.

Strange thing was having this car from new, well I changed the plugs for the first time I found half the plugs were NGK and half DENSO?

[guest4078]

Yes, I have bought sucessfully on e-bay from Micks Garage. No problems.

Also, I bought a set of NGK plugs ( for under £15 on e-bay earlier in the year.

Our 1.2 had a mix of plugs from the factory too, NGK/Denso.

[guest1521]

Is there some material used in the plugs that naturally degrades such that you'd have to swap them out after 2yrs even if you'd only done 10k miles?

Sparkplug change intervals... replacement based on 'time' is p'raps simply an arbitrary way of allowing for cars that do low miles but spend a lot of time idling and/or crawling in stop/start traffic. Such as Tokyo...

It's 'rpm/revs' that wears plugs. They don't simply degrade without use. Their electrodes 'erode' with sparking and, in time, the increased (and increasing) 'gap' puts stress on each sparkplug's coil. (That's long before easy starting, smooth idling and running are affected.)

Unhealthy engines will 'wear' sparkplugs in various other ways. The visual appearance of a sparkplug will give big clues to an engine's health. Google around for website (NGK?) images and explanations.

Jazz original fit sparkplugs are 60,000/75,000 milers, I think.

[guest4283]

Ah yes, what you say makes sense. I couldn't see that sparkplugs would degrade without use. I forgot about idling time. So sparkplugs life should really be rated by 'hours in use' as well as mileage.

The Haynes manuals no longer have a sparkplug diagnosis chart in the back. Although something similar is available here: http://www.aa1car.com/library/reading_spark_plugs.jpg

I'll probably pull the plugs and check the condition & gap when the weather improves.