Are NGK BKR6E spark plugs compatible with an X300 XJ6 4.0 model?


I am currently looking for spark plugs for my '96 X300 XJ6 (4.0 litre model) and I was wondering if NGK BKR6E spark plugs fit the car with no issue.

I was able to find online that NGK BCPR6E are specified spark plugs for X300 model but the specifications are basically the same as BKR6Es, which made me wonder if there is a reason as to why BKR6Es are somehow not recommend or fit for X300.

Have anyone tried using BKR6Es and faced any issue?

The reason behind this question is that in my area, it’s much easier to find BKR6Es.

Stolen from the Audi forum;

bp6es: 14mm, 3/4" reach, 13/16" hex, gasket seat, JIS height, projected tip

bkr6e: 14mm, 3/4" reach, 5/8" hex, gasket seat, ISO length, projected tip, resistor, V-power (v-grooved center electrode)

That all came from

thx for the information!

NGK BKR5e = Champion RC12YC

NGK BKR6e = Champion RC9YC

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I could only find a used BKR6E. The pictures could be better, but hopefululy the differences are visible:

The BKR6E has the V-groove, the hex part is longer on the BCP6ES. From the gasket down the dimensions are identical, so spark position is also identical. The top is about 3mm higher on the BCP6ES, so the spring in the coil will be compressed further. I am not sure if this is required. I’ll measure the champions to see how long those are in comparison.

The AJ16 is the first engine I found to be fussy about spark plugs. It came with newly installed magneti marellis and didn’t idle very well. I installed Bosch plugs and things did improve a little. I then installed champion RC9YC and idle became really bad. Then I dug out some old used BKR6EK which massively improved idle.
The BKR6EK is the twin ground electrode version of the BKR6E, so that can’t be completely wrong…

Thx for the information! helps a lot!

I was wondering which to go for cause I hear both are compatible with AJ16 but now I know the differences.

I’d probably go for BRK6Es!

Best plug for US spec AJ16 engined cars, x300 & later XJS 4.0 is RC12YC.

RC9YC is for AJ6 engines. So is BKR6E.

All of the emission equipped Jaguars, particularly inline 6 cars are picky about spark plugs for a good idle.

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