High mileage 2013 Prius Spark Plugs

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Gloria&Suzanne, Jul 20, 2026 at 3:35 PM.

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  1. Gloria&Suzanne

    Gloria&Suzanne Junior Member

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    As shown in the images below, do you think these spark plugs need replacement? They were oily when I took them out, so I suspect piston ring issues. IMG_20260712_145736213.jpg IMG_20260712_145748306.jpg IMG_20260712_145755261.jpg IMG_20260712_145800068.jpg IMG_20260712_145804800.jpg
     
    #1 Gloria&Suzanne, Jul 20, 2026 at 3:35 PM
  2. BiomedO1

    BiomedO1 Senior Member

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    You need to examine the tips, electrodes and gap. Any damage or pitting, they should be replaced. Iridium plugs will easily go 100+K miles.
     
    #2 BiomedO1, Jul 20, 2026 at 3:45 PM
  3. Brian1954

    Brian1954 Senior Member

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    How many miles have you driven the car using those spark plugs? They look like new.
     
    #3 Brian1954, Jul 20, 2026 at 5:43 PM
    Last edited: Jul 20, 2026 at 8:46 PM
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  4. Gloria&Suzanne

    Gloria&Suzanne Junior Member

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    I suspect mine might have piston ring issues and I wanted to make sure there spark plugs were not fouled by oil. I'm pretty sure they look normal.
     
    #4 Gloria&Suzanne, Jul 20, 2026 at 8:33 PM
  5. bisco

    bisco cookie crumbler

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    gen three up through part of 2014 had poor pistons and rings. have you cleaned the egr circuit?
     
    #5 bisco, Jul 20, 2026 at 8:44 PM
  6. CR94

    CR94 Senior Member

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    Is it consuming much oil?
     
    #6 CR94, Jul 20, 2026 at 9:21 PM
  7. Gloria&Suzanne

    Gloria&Suzanne Junior Member

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    The oil turned dark after only 2k, but I changed it just to be safe. My dad said it can be one of the signs of that happening, or starting to happe. Or maybe the oil was contaminated by the carbon deposit buildup (a known third generation prius problem) that I cleaned a few months ago, a bit after the oil change at Jiffy Lube.
     

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    #7 Gloria&Suzanne, Jul 20, 2026 at 9:56 PM
  8. ASRDogman

    ASRDogman Senior Member

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    Wow, that's dirty. It's not likely the oil was changed often enough, and/or it was the incorrect oil.
    You could use a quart of Marvel Mystery Oil the next time you change the oil.
    And about 3-400 miles before you change it, add 4-5 ounce of SeaFoam to the oil.
    It will help clean out the nasty stuff.
    You could also try Valvoline's Restore and Protect. It won't hurt to use it, and it "might" help
    to clean out the crap.

    Make sure you change the oil every 5000 miles also.

     
    #8 ASRDogman, Jul 20, 2026 at 10:23 PM
  9. Gloria&Suzanne

    Gloria&Suzanne Junior Member

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    This was only 2k miles after it got an oil change at Jiffy Lube. The oil was dark when I drained it out so I changed the oil giving it the right amount and type of oil.
     
    #9 Gloria&Suzanne, Jul 21, 2026 at 12:22 AM
  10. Gloria&Suzanne

    Gloria&Suzanne Junior Member

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    #10 Gloria&Suzanne, Jul 21, 2026 at 12:26 AM
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