Just fitted a new set. Two of the originals, Nos 1 & 2, had completely failed. 3 and 4 were still working but at reduced efficiency. Car has done just over 83k miles. Our previous 1.9 Tid had done just over 107k miles, and was traded in with the original plugs still in place.
I can only assume that, as the first one spent a lot of its time belting up & down A40 & M40 to work and back and this one is used for more local work, more starts may have shortened the life of the plugs. Happily, as we do a 'DPF clean' fortnightly visiting our daughter in Bovingdon, the resultant thrashes on A40, M40, M25 and a bit of A41 ensure there are no problems there.
Easy to remove, but the bleddy things needed a 9mm socket instead of the 10mm one I was expecting to have to use.
The starting had been slow over the last week or so, ie turning over smartly enough but taking many revolutions before firing, even though we religiously use the method of allowing the SID to display 'checks OK' every time before cranking. Now all is well again. Happy.
Pete