I have a 2013 F-150 5.0 V8 with 84,000 miles. Still, have original spark plugs. When should I change them?
runs fine now. Should I wait until they burn out?

Thanks,

 

I'd go ahead and change them now. Always better to do it when your truck is still running than to do it when it isn't. (Normally, spark plugs get changed around 100,000 miles)

 

Right from the owners manual: Every 100000 miles or (160000 km) - Replace spark plugs, Inspect accessory drive belt(s) and Change engine coolant.
But there's nothing wrong with doing those early since every vehicle is driven differently and in different conditions.

 

I'd change them now. In fact I changed mine at 60k miles. Yes the stupid book says 100k but lets be real.... Cheap Insurance

 

100k miles, no need to waste money when not needed.
All plugs I’ve changed at 100k were still good with only re-gapping needed.

If it ain’t broke, don’t fix it.

 

The maintenance recommendation is 100,000 miles, but some of us with the Ecoboost engines have experience significant plug fouling before then. If that happens, you'll know it, because you'll start getting misfires under heavy load or acceleration. I changed my first set of plugs at about 80,000 miles, and just did it again at about 160,000. If you're not experiencing any problems, you can wait until the recommended mileage.

 

I've changed mine at 50k, with 30k worth of tune and they looked OK if I recall. Changed again at 100k and the driver side I had to work them back and forth for fear of galling. I plan on chagning every 50k just so they don't sieze up. But I've also changed my tranny fluid at 60k and 100k. I don't care what the owners manual says, after 60k (actually 20k) my truck wasn't a liability to them anymore and I choose basic preventive maintance over what ford says when it on my dime.

 

Re-Gapping a modern day Platinum or Iridium tipped spark plug is NOT recommended by any Manufacturer

 

You miss the point, of course I would never re-use 100k mile spark plugs, point being they still worked fine except the gap needed changing IF one was going to reuse them.

No need to change them before then.

 

I changed mine at 65K. I bought the plugs at a good price and changed them myself. I will change again at 130k. The gaps were over spec. I considered it money well spent.