Check your spark plugs
 

I replaced my valve cover gasket yesterday and went ahead and replaced my spark plugs as well. Even though the car ('06 3.0i, 219k miles) was running fine, it'd been about 75k miles since I replaced them.

Couldn't believe what I saw. That's like a 2mm gap (NGK Iridium). All the spark plugs looked like this. Can't believe it wasn't misfiring. Anyhow, thought I'd share and am looking forward to seeing if replacement improves my MPG going forward (TBD).

https://live.staticflickr.com/65535/...9c6cfb06_m.jpg

For sure! I don't drive plugs too far. I replace them between 30k and 50k miles. Depends on the vehicle. The X5 had some bad ones. I think it's the reason coil #3 was starting to fail. It looked the worst. I upgraded to the Iridium set. The 3.0i ran smooth with the old plugs. It runs even better now with new coils and plugs. MPG is up too. Even more with a new thermostat.

You are passed their due dates according to NGK => https://www.ngk.com/how-long-do-ngk-iridium-plugs-last

Yup, Dodge uses NGK as stock plugs. The manual said every 30k miles on my Nitro. The plugs barely made it to 25k miles. City miles worn them down good. So I started to change them at 25k miles. My old Ram was the same way. 25k mile new plug maintenance. The X5 will get a new set again at 175k miles. 25k mile replacement is good maintenance. Easier on the coils tool.

The OE laser platinum that came with the X5 last a pretty long time - rated for 100k miles. They still look decent when I had initially swap them out at 60k, but I wanted to do it mostly just so they wouldn't get "welded" to the head. After that, I made it a maintenance item at every 60k - 70k miles.

Thanks all for the responses. I noticed the platinum ground ones last much longer in the link posted by dkl too (my next set if it makes it past 260k).

I admit I waited too long to replace them and I expected some wear. I was just amazed (or was ignorant to the fact) that a car could still run without any misfires or codes with a 2mm+ gap in all the spark plugs when recommended gaps are less than a 1/4 of that.