| Most "NGK"s are copies, not original items from the NGK factory. They can have the wrong heat rating and leak out pressure. This pic shows the fake one I bought that had "painted" metal that flaked off a little on the ground electrode. After riding with it 2 miles it showed no deposits on any of it, probably because it got too hot to allow them, that and the fact that the painted metal prevented deposits. The true one (iridium) on the left shows normal deposits.  On my video about this topic I said it was probable that all the fake copies were different than their heat range # indicated. Well, I just measured the distance from the threaded body end to where the ceramic contacts the metal and found that the copies were significantly longer. I had cut a strip of thin plastic from a plastic drinking bottle 5mm wide and 35mm long and inserted it into the plug body to measure distance A. I used a black marker to mark the plastic even with the end of the plug body. Here's the results below. The fake NGK's all had distances more than the genuine NGKs which means they will all run hotter and possibly cause auto-ignition. The longer the distance is that the ceramic is exposed to the combustion heat/pressure, the more heat they absorb.   NGK's website gave this list of authorized dealers but my last order of NGK plugs from AutoZone was fulfilled with non-genuine NGK's. Dennis Kirk isn't on their approved list and I've also bought fake NGK's from them.  Here's the listed prices for a NGK BR8HS #4322: Summit Racing $2.99, Advance Auto Parts $3.99, O'Reilly Auto Parts $4.49, NAPA $4.29, Dennis Kirk $3.56 Here's the listed prices for a Denso IWF24 #5380 (sub for NGK #BR8HIX) : O'Reilly Auto Parts $9.99, NAPA $13.99 NGK code chart: click here  |