NGK Iridium spark plugs

Jaguar5993 · Postby **Jaguar5993** » Fri Apr 10, 2009 3:02 pm

I am thinking of replacing my NGK BR7EF(BR6EF 11/94 onwards),on my 1995 6.0 coupe with Iridium plugs.I like the tech. spec. of them and the fact that they normally last for about 60.000 miles before a change.
The problem I have ,apart from the £70 for the 12, is that NGK are listing BPR5EIX Iridium plugs for the V12 XJS upto 1981(pre HE I guess),but they are N/A for my model, although they will stock them for all other Jags old and new !
Doe's anyone know why?Do they not agree with the ECU?Is there no benefit in changing for them?I am certain they are not Iridium already.
Any info would be great.
Nick
XJS V12 6.0 95N

simon4253 · Postby **simon4253** » Fri Apr 10, 2009 9:51 pm

do you just want the 60000 mile change and are you doing that many miles? A lot of new cars use platinum or iridium plugs but v12,s run very rich on startup and this can kill ngk plugs very quickly. If your car has ecu controlled ignition you may get decent mileage from these plugs but short journeys and or running faults may kill them as quickly as standard plugs.for normal road use you are unlikely to notice any driving difference but if you pay someone else to change your plugs you may save money but otherwise fix any faults and enjoy using cheap plugs as the manufacturer didn,t just guess at what was suitable

Jaguar5993 · Postby **Jaguar5993** » Sat Apr 11, 2009 7:52 am

Thanks Simon for the reply so quickly.
I only do 5000 miles per year,so the Iridium plugs ,I hope, would be in for some time.
I was mainly interested in why NGK only listed these plugs (BPR5EIX that replaces standard BP5E plugs)for the V12 XJS upto 1981 and not the late models.
I have also emailed Dave Marks on the subject.

Many thanks

Nick

XJS 6.0 95N

Jaguar5993 · Postby **Jaguar5993** » Tue Apr 14, 2009 1:43 pm

Since writing my first post on this subject I have just heard back from NGK Uk (I should of asked them first!)
They have said that they do not produce a suitable upgrade spark plug for my model of XJS, due to the fact that it uses a taper seat style plug which is less common than the gasket seal style.
I am guessing ,if they did supply these plugs in the future, it would be ok to use Iridium and gain some benefits??

Nick
XJS 6.0 Coupe 95N