Go to Maintenance Information Page


Spark Plug Specifications


KJ-ZEM Engine - 2.3L V6 (Miller Cycle)

Gap specification:  0.7 - 0.8 mm (0.028 - 0.031 in)

Platinum - KJ OE Heat Range (Stock Number) One Range Colder (Stock Number)
Denso PKJ16CR8 (3175) PKJ20CR8 (3173)


KL-DE Engine - 2.5L V6

Gap specification:  1.0 - 1.1 mm (0.040 - 0.043 in)

Platinum - KL OE Heat Range (Stock Number) One Range Colder (Stock Number)
NGK PZFR5F-11 (4363) PZFR6F-11 (3271)
Denso PKJ16CR-L11 (3246) PKJ20CR-L11 (3247)
Champion RC10PYP4 (7346) RC8PYP4 (7345)


Standard - KL OE Heat Range (Stock Number) One Range Colder (Stock Number)
NGK ZFR5F-11 (2262) ZFR6F-11 (4291)
Denso KJ16CR-L11 (3131) KJ20CR-L11 (3133)
Champion RC10MC4 RC8MCC


Change Intervals

Standard Type - 48,000 kilometers (30,000 miles)

Platinum Type - 96,000 kilometers (60,000 miles)



Plug recommendations for the KJ are straight from the Owner's Manual with stock numbers added from cross-reference listings found online.  Only the NGK part numbers are specified for the KL in the Owner's Manual, with Denso/Champion part numbers and stock numbers matched from cross-reference listings found online.  Use of plugs from other manufacturers should be used with caution on the KJ engine as incorrect gap or heat range specifications can cause misfire and/or ignition coil damage.

Information on spark plug heat ranges - Colder range plugs are less prone to knock due to "hot spot" pre-ignition, and better for performance applications.  Hotter ranges are less prone to carbon fouling, which can cause misfire.

OE heat range vs. one range colder  - Auto manufacturers typically fall to the slightly hotter end of the range for an application in case a car gets driven extensively on the highway for thousands of miles with barely a blip of the throttle or driven for prolonged periods at slow speeds and low rpms where combustion conditions make spark plugs prone to carbon fouling.

Generally, it is best to use the coldest recommended heat range plug that will stay clean under current driving conditions.  Fouling is easy to check for visually after using a colder heat range plug for a while.


[Mazda Millenia Spark Plug Information]