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OEM Recommended NGK Spark Plug Part Number Change

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Auto Engineer, Dec 12, 2010.

  1. Auto Engineer

    Auto Engineer Enthusiast, Engineer, Mechanic

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    Hey everyone,

    Upon researching spark plugs for the Prius, I found that one of the two plugs recommended in the owners manual has been replaced by a new part number. The owners manual recommends DENSO SK16R11 or NGK IFR5A11. Both of these plugs are iridium with platinum, designed for longevity. I have used Denso IK-series iridium plugs in performance cars (high compression and turbocharged) with great results.

    According to an NGK document, the IFR5A11 has been replaced by the IFR5T11. The original source from NGK is the following link: www.ngkntk.co.uk/working/FileLib/1010 IFR5T11 Spark Plug.pdf

    This link may change in the future, so I attached the NGK document in a PDF format.
     

    Attached Files:

    #1 Auto Engineer, Dec 12, 2010
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  2. Auto Engineer

    Auto Engineer Enthusiast, Engineer, Mechanic

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    Also, the NGK IFR5T11 spark plugs are available at Amazon for $7.73 (as of 12-14-2010) and free super saver shipping. So you can get a full set for under $31.
     
    #2 Auto Engineer, Dec 14, 2010
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  3. PriusCamper

    PriusCamper Senior Member

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    Just bought NGK Iridium stock #5464 BKR5EIX-11 This is what AutoZone claims is for a 2007 GenII Prius... I've found some confirmation online, have yet to find confirmation on Prius Chat... NGK really doesn't need to change the numbers around again and again do they?
     
    #3 PriusCamper, Aug 25, 2012
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    That plug would not be my first choice. While it will "fit" and will "work", I believe it will have a shorter service life compared to the correct NGK IFR5T11 plug. The correct iridium plug has a platinum disc attached to the ground electrode.

    If you look at the NGK website you will see that NGK produces an Iridium OE plug model, which offers very long service life, and an Iridium "performance" plug model. The plug that you bought appears to be in the latter category.
     
    #4 Patrick Wong, Aug 25, 2012
    ovianc and PriusCamper like this.
  5. PriusCamper

    PriusCamper Senior Member

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    Wow... Thanks Patrick... So grateful for your reply... More and more I'm thinking the best perk of being a Prius owner is the smart-folks on PriusChat.

    Will both plugs give the same gas mileage?
    Is the only difference being durability?
    Cause knowing me I'll likely change my plugs out way sooner than 117K from now... :) I mean I've only had the car for 15K and I have endless fix up ideas for it... Most of all I still can't get over that spark plugs will last that long. What's next? Tires that never wear out? :)
     
    #5 PriusCamper, Aug 25, 2012
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  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Will both plugs give the same gas mileage? Yes
    Is the only difference being durability? Yes. I haven't seen a specific durability claim for the performance Iridium plug, so my guess is that it may last 60K miles.
     
    #6 Patrick Wong, Aug 25, 2012
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  7. PriusCamper

    PriusCamper Senior Member

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    Thanks Patrick, Auto Zone said the plugs you recommend would be a special order and cost a couple bucks more than the ones I bought... And 60k miles on a set of plugs is probably good enough for me because I love working on my car and I'll likely have plenty of opportunities to replace plugs with the better ones down the road.

    QUESTION: Auto Zone guy said recommended gap is .44 ? Is that ideal? I've had cars in the past that burned a little cleaner/slight MPG improvement when I made the gap bigger than recommended. Is that the case with this car too?
     
    #7 PriusCamper, Aug 27, 2012
  8. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The correct spark gap spec is 1 mm to 1.1 mm. 0.044" is slightly more than 1.1 mm.

    I usually set my plugs to the minimum 1 mm spec, under the assumption that the gap will grow over the plug service life.
     
    #8 Patrick Wong, Aug 27, 2012
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  9. RubberToe AS

    RubberToe AS Junior Member

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    Hi Prius Camper,
    I also want to replace my 2008 Prius with new spark plugs. Can you please share your experience of using this type of performance spark plugs? I understand that they have a shorter life span than stock but if they provide better performance in terms of response gain or fuel efficiency, it might be worth considering.
    I appreciate your comments.
    thanks, RubberToe
     
    #9 RubberToe AS, May 3, 2016
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