Should I change the spark plugs now at 112K or wait to get to 120K?

 

have they ever been changed?

 

Take one out and look at it. I suspect you are running the second set of NGK platinums and probably have no idea when the first set was changed out.

I am a firm believer that the NGK platinum plugs used in 4th Gens are good for more than 60K. Two months ago, my friend and I took my OEM plugs out, cleaned them up on a wheel and put them back in. They are good to go and have just under 58,500 miles on them, albeit mostly highway. My friend's brother cleaned his up at the same time on his 99 Maxima with 78K on it. He bought the car two years ago at about 56K and I would be willing to bet his plugs were original. They are also good to go and he has been running nothing but 87 octane in the two years he has owned the car.

I'm not suggesting you clean the plugs up on a wheel, but you should at least take a look at one. I highly suspect they are good to go until the 120K service and perhaps longer.

My fuel economy is very good relative to other .orgers and my throttle body and IACV have never been cleaned. If it ain't broke, don't fix it!

 

Yes, at 60K with OEM NGK platinum.
My question is whether it will make any difference or the plugs are as good the last 10K of their life as they were in the first 0-50K. Do they start to get weaker before 60K comes around or do they start losing their spark only after they reach 60K.

 

DO THEM NOW!

What are we talking about, price-wise? About 25 bucks?

Unless you are on a really, tight budget, why not change them now. It is a fairly, easy DIY job.

On the other hand, 10 months from now when you hit 120K, you really may not be able to afford them! (Hopefully not, of course)

So, why wait? New plugs will make your car run quieter and cleaner right now. Plus, you will not have to worry about them again for another 5-7 years.

Time, more than mileage, is a greater concern. Over time, hairline cracks appear on the ceramic, dirt builds up in the well surrounding the electrodes, corrosion forms on the connector tip, and carbon builds up on the electrode.

Just my 2 shekels.

 

My OEM plugs have been in my car since the day I picked it up, October 1, 1994. The car idles so quietly I have to look at the tach at a stop light to ensure it is running. My fuel economy is as good as its ever been. I have exceeded 550 miles to a tank of gas twice.

If I notice my fuel economy is lower on my annual 500 mile round trip to my sister's this summer, the plugs will be given the hook, but not a day earlier. I intend to replace them with NGK platinums which are considerably more than $25, more like Cdn$100 where I live.

However, I am a lot more **** when it comes to routine, frequent fluid replacement (oil, radiator, transaxle, power steering, clutch).