Anyone use NGK Iridium plugs, what heat range?
I have a 97 XJ6 and haven't changed the plugs in 3 years.

Wanted to go with NGK Iridium IX, but I get 2 different part numbers.
The NGK website says to go with BKR6EIX, while the lady at Canadian Tire said her system gives BKR5EIX, a 1 range point colder plug.

Any idea what the correct plug is for that engine?

There was also a link on the NGK site that talked about using a colder plug when you have 10% ethanol in your gas.

Much of our gas in Western Canada is now a 10% ethanol blend, so should I then be using a colder plug such as the BKR5EIX.

I was also told that the Champion Iridiums are just as good, and they cost 20% less.

What specific plugs should I use for every day driving, mostly city but also long drives on the highway on weekends?

Thanks,
Kevin

 

I have 'em (BKR6EIX) in my XJR and they're fine.

Part of the confusion in the listings might come from a Jag tech bulletin...which recommended a hotter plug for some XJ6s.

I'm pretty sure that, with NGK, a lower number is a hotter plug....unlike the convention used by other plug manufacturers. Someone might come along and verify that..or not :-)

Cheers
DD

 

I ordered the BR6EIX in January for my 95 VDP 4.0L.

Haven't put them in yet. Most likely in June. Approaching 85k mi acquired car at 63k. Don't know if original or not.
_____________________
Installed 6/12. 85,067 mi

So far so perfect....but no problems with the champions I removed, either...just figured it was time....(and I never liked Champions since #8 failed twice in rapid succession when the CJ7 was still in warranty)

 

I have a 1995 xj6 also with 183k miles on it i just put the champions, that the manual said, humm just wondering if i should change again please advise, there easy to do i also work for one of the top 3 automotive suppliers in usa, so the cost is nothing for me let know you all if you think i should put different plugs in, maybe get alittle better gas mileage???

 

Surely the correct type of plug is very dependent upon such things as engine size, compression ratio etc: just asking "what is the best plug for my XJ6" is an impossible question to answer.
Engineers or others with technical knowledge please feel free to say I'm way out on this!
My experience with cars over many years has taught me that the choice of correct SP is on the one hand a science and on the other a maze of confusion.
The best thing would be to get the SP recommended in the handbook for your own specific model. Difficulties then arise of course if that particular plug has been discontinued or dropped from the manufacturers' range and that's where you enter the maze searching for alternatives!

 

Using whatever is listed in the manual is certainly the safest bet....but perhaps not always the best bet, if you get the distinction.

I don't know WHY Jaguar used Champion plugs. After exhaustive testing did they determine Champions really DO work best? Or was it price, contractual obligations, and supplier logistics...together with a "Champions will get the job done" philosophy that forced the decision? Without that knowledge it's impossible to say how important it is to use them today even though Jaguar used them umpteen years ago.

Were iridium plugs available in the mid 90s? I don't know, but, if they were, why didn't Jaguar use them? Poor test results? Or good test results but simply too expensive? Or inadequate supply and/or other business considerations? Without those answers it's impossible to say if iridium plugs should be avoided.

The same could be said for tires, oil, filters, etc. Presumably all are chosen, from the offerings available at the time, as the best compromise between price and performance and are known to give satisfactory results.

But Jaguar is not in the parts testing business and have no interest in helping us decide in what alternatives might be better, thus the advice, as with all manufacturers, to stay with "factory recommendations". That's the safest, easiest answer for them. It's also the safest and easiest answer for US.....although perhaps not always the best answer.

So we try different plugs, tires, etc., often using anecdotal evidence to help our own decisions along, at our own risk and with varied results :-)

Cheers
DD

 

In my opinion, iridium plugs are not good for X300s. I don't think it is good for older cars. I once put NGK iridium plugs, BKR6EIX, but normal plug is much better. It is a kind of pain in the *** to change plug every 15000miles, so I install Bosch platinum plugs now.

 

Are you saying the NGKs needed to be replaced after just 15K miles? If so, why?

Cheers
DD

 

NGK higher number is colder

 

Sorry, I should have stated which manufacturer or model spark plug works best. There have been many new products in the last 15 years and there are in fact many different choices of spark plugs specifically rated for an 97 XJ6, from many different manufacturers.

My local Jaguar dealer recommended NGK for example. With in NGK's product line there are a wide variety of choices in materials and models, all which are considered a fit for that car. Since Platinum was older technology, I went with the Iridium IX BKR6EIX, which NGK lists as the specific recommended plugs for a 97 Jaguar XJ6.

They seem to be working just fine, did a road trip and averaged 9 litres per 100 kms on Chevron 94. That works out to 26 MPG US on the highway and I experienced a definite performance gain compared to the 3 year old, non Iridium plugs.

 

Doug,

Normal register plugs last only for 30000km or so, aren't they?
Only platinum ones and Iridium toughs last for 100000km.
Even the normal iridium plugs you have to change them every 30000km.

I heard that at first iridium plugs were made only for racing cars which used their plugs for only one race because of its short lives.

 

My experience with any modern car with fuel injection and electronic ignition is that the standard type spark plugs last at least 30k miles (48000 km)....and often longer.





I really hadn't heard anything about iridium plgs having such a short service life. But since you've mentioned it I'll remove mine for inspection....they have about 48000km on them. We'll see how they look!

If it's true that they have a short service life it'e difficult to justify the $6.00/each price tag, that's for sure.


Cheers
DD

 

I installed a set of these a week or two ago. Have burned a tankful on 'em and they seem fine. Replaced Champions that were apparently original. Didn't take note of the numbers..but I still have them. No problems with running or idle, I just changed b/c it has 85k mi...(I got the car at 63k..they may've been changed previously) and used NGK Iridiums because I've really no use for Champions (though I grant they ran fine for the 22k I put on this car) and got a good deal, think about $3/ea counting rebate, and had heard Bosch has caused problems in X300's...did install a set of Bosch Iridiums (another good deal) in the daughter's S-Type 3.0L in Jan. and it is doing fine.

 

Doug,

Sorry but I am actually not sure how and what products they sell out there, but at least they sell a couple kinds of iridium plugs in Japan. Mainly two types; the one having shorter life but better performance - mainly used in race / the one having longer life but normal performance.

 

For months I had a stalling problem on my XJ6 96'. The car would stall at idle for no apparent reason. I replaced the fuel filter, air filter, cleaned the throttle and nothing. Took it to a mechanic (not a Jaguar specialist) and couldn't find the problem. I check on this forum and someone asked me about the plugs. I had changed them before (putting Iridium plugs). After I replaced the Iridiums with Champions the problem was fixed. I don't know if this occurs with other Jaguars x300, but I know the same stalling problem has been fixed, at least a couple times (check this forum). Bottom line, I don't recommend Iridiums, there were a mess for me.

 

I think this also applies to XJ40s . I appreciate your message , it's good to see you fixed that stalling issue by just changing the plugs

 

I just installed Bosch platinum plugs in my 96 XJ6, it quieted it down a little, gave it more push in the pedal and I'm pretty happy.

 

Great , happy driving

 

lol - were you being sarcastic? Or do you think these are good plugs?

 

You don't say what make or model Iridiums that you used, there are many different choices.

This original post was about a specific Iridium plug and heat range. Champion also makes an Iridium plug, so you didn't qualify your particular situation.

Iridium is related to platinum, but denser and capable of higher heat. It is used in aircraft engines, computer chips and lasers because it is much harder than platinum and it doesn't corrode.

I don't know if it was a coincidence, but it seems odd that your stalling problems were a result of your spark plugs unless you used the wrong gap or heat range. Or perhaps something else was loose or not connected properly and this was rectified when you changing the plugs.

A spark plug fires unless it's fouled or doesn't get current. You have to use the specific plug, gap and heat range designed for your engine. The spark plug material is not likely the issue, except in relation to longevity.