I believe that two of them were supposedely replaced by the dealership during a de-flooding procedure.

One of the trailing plugs was completely black while the other trailing plug was black but also had some corrosion. Could this discrepancy between the two be cause for any concern?

 

Trailing, Trailing, Leading, Leading

 

Hopefully you're talking kilometers since 35K miles is the change point in the manual.

 

^dude you be surprised, mine lasted just as long....

 

nope they are at around 64,000 kilometers/5 years old and were running fine

what kind of wear does a worn spark plug produce? i can't imagine any wear if the plugs are still firing fine

 

Try to push them, u will know how bad they're

 

None that you'd be able to see in that picture without sending it to NASA.

Too dark and small to see any detail, sorry. But that's usually the case when people submit pictures of their plugs.

The wear occurs on the electrodes, as each spark erodes a tiny bit of metal. Since the center electrode is Iridium, and about the toughest metal there is, the side electrode is usually the one to wear away.

The "corrosion" you see is likely to be just ash deposits from oil burnoff and usually its not in a location that causes problems.

There are other problems that can develop over time such as glazing, carbon-tracks, cracks, etc.. You've got your money's worth from these plugs. Don't be greedy

 

note to all.

really..

20k miles is pushing it unless you track often..

beers

 

I do mine at roughly 30 000mi/45 000kms, along with coils and wires, they looked like that to

 

Update:
My idle has improved significantly. It used to fluctuate quite a bit but is now steady and very smooth.

Have to move onto the coils and plug wires next. BHR or LS2 Coils?