Seeing this thread I chose to renew the NGK plugs on the Duratec 1800cc 4/4 (2008). At 48,745 miles they were quite easy to remove by 16mm long reach socket. Only the plug nearest to the radiator showed any sign of corrosion. The gaps were between 1.5mm and 1.75mm.
Noticeable improvement gained to starting which is now instantaneous on turning key. The starting was already good but not this good.
[img:center]
https://photos.google.com/search/_tra_/photo/AF1QipOygBBPybUnHnoN8vQmfWp9wQnyZoq4ONBHZD8T[/img]
Part number from Spark /Plugs Ltd is ITR6F13
