Apologies in advance for dragging up this "which spark plug" question, but looking at previous threads still confuses me.
When I search online for the spark plugs for my 1995 X300 4.0 litre, I am advised that Champion RC9YCC are recommended. However, my handbook recommends RC89 PYC, the latter being platinum and more expensive than the others.
Anyone clarify or advise please?
Thanks.

 

Hmmmmm

Just checked my owners manual and it calls for RC9YCC for all of the 6 cylinder X300s.

Where are you located? I wonder if this varies by market?

Various technical bulletins from Jaguar mention only standard type Champions....although a higher heat range was recommended.

I'd go with standard type plugs and see how you like 'em. Personally I've tried both standard Champions and platinum NGKs and couldn't see/feel/hear any difference in the way the car performed.

Others, though, report quite the opposite with some reporting much better results with one type or the other.

I can't explain it.

Cheers
DD

 

Thanks Doug, appreciated.
The plot thickens somewhat as, although myself and the car are in Spain, it was originally registered in Florida USA and the owner's 'Vehicle Care' book originates from there so it's a bit odd that your book's recommendations differ from mine.
We are talking about the 4.0 litre are we? If so, my confusion is perhaps understandable!
Thanks again.

 

Page 82 ??




Yes. 4.0 engine :-)

Cheers
DD

 

My 1995 XJR Canadian manual shows the above as correct, too, only it's on page 84.

 

A big thanks to those who've responded.
Shaune, I'm looking at page 84 of my book now and it says Champion RC89 PYC for both the normal and supercharged models.
Odd!

 

There was a lengthy discussion here last summer and it was concluded that the proper plug was the RC12YCC in accordance with Tech bulletin 18-56. To check this just enter the plug number in the forum search. This is a hotter plug.

 

Found it thanks. Much appreciated.

 

Yes, odd.

It appears that Jaguar had a change of heart about spark plugs....or perhaps some manuals were published with incorrect info? Or...who knows? With enough time and effort we could probably get to the bottom of this mystery.

But, it's of little consequence in the grand scheme of things. It does pique my curiosity a bit, though :-)

Cheers
DD

 

Thanks again Doug. I don't know enough about spark plugs to answer my own thoughts here, but I wonder what difference the RC89 PYC type makes if, Jaguar had a 'change of heart'? If it is a typo or other error, could fitting these cause problems? Just wondering, but I don't intend to try.

 

I replaced with the 12 series except for a single, not dual C on the end. Single c easy find double C not so much. After a few months very happy, 96 4.0 six

 

I've recently occasionally obtained a NOS set of EBC8143 which by bulletin should be installed to all 4.0 engines and they look like this

 

Those are the exact plugs I installed, gapped to .035", run great. Have been advised against the new premo stuff (iridium etc) as they are reported to idle poorly.

 

Those are the exact plugs I installed, gapped to .035", run great. Have been advised against the new premo stuff (iridium etc) as they are reported to idle poorly.