Spark plugs
 

How often do you change them? It occurred to me that I am pretty much the one who maintains my Z. I do my own oil changes and various lubrication on suspension bits etc.

I'm just shy of 20k miles and I have never changed out the plugs. It has been to the track 3 times. Other than that, normal to spirited driving. Not a whole hell of a lot of highway miles. I've got no misfires, hard starts or anything like that.

So when should the plugs get changed? Which plugs are best? :confused:

I don't have a solid answer for you except to say that if it ain't broke don't fix it.

If your gas mileage is good and all other things are fine then I'd leave it.

I do believe that the plugs should be good for at least 50,000 miles.

I usually do everything in half the time the manual states. That's me though being I beat up on my car more. Being my car has been tuned I'll monitor my A/F every so often. Then I'll base those results on on if I need to change the plugs sooner. If you were FI porbably around 15k miles is what I was recommended on my 350.

Thanks guys. I'm not FI but do have a tune and need to find a way to monitor A/F ratios. Aside from that, mileage seems fine. I guess I'm good to go for a bit longer.

they are iridium, i think they are rated for 90k from the factory. i believe the z comes with a factory wideband? (confirm if i am wrong), you should be able to get a rough idea using an obd2 scanner

If your mods are not extreme, just read the manual and follow what they recommend.

Yes, the 370Z has two wideband O2 sensors aka air-fuel ratio sensors...
R and L part number: 22693-1NA0A $336 ea

I'm going to try some NGK copper sparkplugs (one step warmer) out in the spring of 2012.

Copper isn't a good idea unless you plan to change your plugs annually.

The stock iridium plugs are rated for 100K miles. I've pulled iridium plugs in some street cars after 100K miles and they still looked great. Lots of track will shorten your life expectancy, but as long as your lot running too rich they should still be good for quite a while.