NGK (7164) TR55IX IX Iridium Spark Plug, Pack of 1

Very nice plug.

I put these in a 2001 Cadillac Eldorado, Northstar V8.

I've driven 3000 miles, I'm getting 25 to the gallon, and the car is running great.

I'm very pleased. These might seem pricey, but they are actually reasonable compared to other premium Iridium Plugs for luxury vehicle applications.

I would buy these again, and will be looking at NGK Iridium when I buy plugs for my other rides.

With delco OEM replacement plugs i was getting 17/23 (cty/hwy) MPG on my 2.4L grand am (and during the 140k miles I changed the plugs 3 times with OEM parts and same bad gas mileage each time.) With these plugs and a performance air filter I am getting 23/30! Oh the money I could of saved getting these 7 years ago!

Get them, you won't regret it!

I was not aware that this model of NGK Iridium plugs is only Iridium on the tip and not on the ground electrode. And I didn't know when I bought it that would matter. My 2001 Grand AM V6 3400 engine uses GM's Waste Spark system. Which is a dual firing ignition so the 2nd spark burns excess fuel for better efficiency. Other brands and models have similar systems. When the 2nd spark ignites from the opposite direction which causes wear to the ground electrode. Which means this plug will work, but the poor 2nd spark can cause very minor idle inconsistencies that you likely won't notice unless you know what to listen for. But overall it will wear out the plugs much faster which defeats the point of Iridium in the first place. So if you have a dual firing spark system, spend the money and get either Double Platinums or Double Iridium plugs. I ended up getting the OEM AC Delco Pro plugs for my Grand Am which are a Double Platinum 100,000 mile plug. And those work great in my car...Read more