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spark plug NGK IFR5A11 or Denso SK16R11?

Discussion in 'Gen II Prius Care, Maintenance and Troubleshooting' started by whodat, May 16, 2010.

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  1. whodat

    whodat Member

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    Anyone know which spark plug is better?
    NGK IFR5A11

    or

    Denso SK16R11

    There's a web blurb that says the core metal diameter is different between the types of spark plugs.
    Thanks
    Dave
  2. Mylar

    Mylar Member

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    I just pulled the OEM plugs out of my 2006 Prius after 92,200 miles. They were NGK IFR5A11's. The plugs were fouled and didn't look 'new' like others on PC claimed theirs to be.

    I replaced them with Denso SK16R11 plugs. Unfortunately I won't be able to update you with which plugs are better until I pull these out in another 92,200 miles.

    I can tell you this, I haven't noticed any difference in the car. It seems to run the same as it did with the OEM plugs.

    You can purchase the Denso's on Amazon.com:

    http://www.amazon.com/dp/product/B005BEL0K4?tag=priuschatcom-20
  3. seilerts

    seilerts Battery Curmudgeon

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    Pictures!!! Fouling is usually not the plug's fault.
    uart likes this.
  4. Mylar

    Mylar Member

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    I've got the old plugs here. I'll take some pics and upload them in a few hours.
  5. Mylar

    Mylar Member

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    Here are two pictures of the OEM spark plugs removed from my 2006 Prius with 92,200 miles on it. I change the oil once a month which averages to be approx every 2,000 miles. The engine is not burning oil, nor losing coolant.

    [​IMG]

    [​IMG]

    Mylar
  6. seilerts

    seilerts Battery Curmudgeon

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    These look typical. What is it in particular about their condition that doesn't look right?
  7. tv4fish

    tv4fish Member

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    What makes you say that those plugs are fouled - they look fine to me also.
  8. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Regarding the OP's query, I would say that either the NGK or the Denso plug would be fine.



    Judging from the photos that you provided and your observation that there is no driveability difference, I would say that the old plugs were not fouled. Fouling usually means that the white ceramic insulator is coated with engine oil or some other deposit which prevents proper sparking.



    I'm wondering why you feel the need to change the oil at 2K mile intervals. 5K mile intervals for a quality brand mineral oil or 7.5K mile intervals for a quality brand synthetic oil would be fine, some go even longer between changes.
  9. Mylar

    Mylar Member

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    Before changing out the spark plugs I read a few forums on PC where some of the authors stated they didn't change out the plugs until 120K miles and when they did, they still appeared 'new'. Perhaps using the word 'fouled' isn't the proper term. I was just expecting them to be in better condition. I'm glad to learn that the plugs look 'typical'.

    I change my oil once a month no matter what, typically that results in changing it every 2,000 miles but that varies. One of the main reasons I change it so often is the fact that my last car, a 1999 Toyota Corolla started burning oil and I want to make sure I don't have similar issues with my Prius. Another reason is, I currently live in Pittsburgh, PA and travel back to Cincinnati, OH once a month to visit family and friends. All of my car care products are in my parents garage so I have made it a routine that every time I come home, I change the oil in my car.

    I use Castrol GTX High Milage 5w-30 Motor Oil. I would prefer to use synthetic but that is when my Corolla started burning oil, when I switched to synthetic, so I only use standard motor oil in the Prius.

    Mylar
  10. richard schumacher

    richard schumacher shortbus driver

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    Your 12-year-old experience is misleading you. 5k to 10k miles between synthetic oil changes is fine in a Prius.
  11. Mylar

    Mylar Member

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    I disagree. My personal experience using Synthetic Motor Oil tells me to keep it away from my car. Since I change the oil so often, it would be a waste of $$ to use it.

    Mylar
  12. uart

    uart Senior Member

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    Yeah the guys saying "looked like new" were probably exaggerating a bit. But remember that these things have been in the hottest part of the combustion chamber for nearly 100,000 miles, so all things considered they look good. The light powdery looking grey-white coating is actually a good sign. That's what plugs look like when they're running at the correct temperature and in an engine that's in good condition. Also there's plenty of "meat" remaining on the electrodes.

    Things you're looking for on bag plugs are excessive burning and blistering of the insulator (too hot), excessive oil and damp looking deposits (too cold or engine in poor health) or excessive electrode wear. Your plugs had none of those signs. :D



    Nothing wrong with what you're doing, that oil will do just fine. You could however easily stretch that out to every second month if you wanted to save a bit of oil and yourself a bit of time.
  13. SDprius3

    SDprius3 New Member

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    Plugs look fine. I prefer NGK. As far as oil changes, switch out your oil drain plug for a magnetic one (don't forget to buy the washer too) it pulls any small metal shards from the engine to the plug. Keeps the engine clean and prevents possible issues. Costs about $6.
  14. Mylar

    Mylar Member

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    Thanks for the advice. I've been using a magnetic drain plug for approx. 3 months now. The first time I removed it there was quite a bit of metal on the magnet, this past oil change there was hardly any. I am assuming I got most of the metal that was floating around in the bottom of the drain pan out by now.

    Mylar
  15. Mylar

    Mylar Member

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    I decided to change the spark plugs once again on my 2006 Toyota Prius. The first time they were replaced was at 92K miles. My car now has 128K miles on it. When I changed them out at 92K I used Denso SK16R11's. This time I used NGK IFR5T11's. Attached is a pic of the old plugs after 36K miles.

    [​IMG]

    I honestly think the plugs removed after 92K miles looked better than theses plugs. Check out my preious post above and you be the judge.

    Mylar
  16. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I don't see anything wrong with the Denso SK16R11 plugs except that they show a rust stain on the porcelain insulator, which indicates some water is leaking into the spark plug wells. This is not the fault of the plugs.
  17. uart

    uart Senior Member

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    They look fine except for the rust marks on the porcelain insulators. Check for water dripping through near the cowling under the wipers, several people have reported ingress of water here. If you have the car parked in some heavy rain, or straight after you've been through a car wash etc, then take a quick look at that little recessed trough area in the rocker cover (where the igniters are). You might find you're getting water puddling in there.

    BTW. I'm guessing from the amount of rust staining that the plugs are shown in your picture with #1 plug on the right hand side and #4 plug on the left. Number 1 plug (closest to the pulley belt end) seems to be where the water accumulates most.

    As for the condition of the plugs in general, you need to look at the "business end" to evaluate what's going on. Take a look at the zoomed in area (taken from your pic, 2nd from left) below. Really it's still very good. The electrodes show little to no wear, and the insulator shows only a light grey coating, which is actually what it's supposed to look like. :)

    plug electrode zoom.jpg
  18. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

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    Dang...can you start sending me your used spark plugs?? lol. Those Denso's with 30k miles actually look to be in very good shape. I'd run those bad boys for another 70k miles easy!
  19. Mylar

    Mylar Member

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    Autozone was running a special. The plugs came with a $10 mail in rebate which knocked the price down to $26 for a set of 4.
  20. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

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    But your used ones are still brand new and I'd rather have yours for free (well, FINE - Ill cover postage) :rolleyes:
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