Longest you’ve seen someone go on a set of spark plugs

[doublebase]

I went 149K on my LS1 F-body, and it never lost any measurably performance or mpg. My Dad's 438K mile old work van, I will ask if he ever changed the plugs, lol!

Work vans have the craziest history, used to know a hvac guy that worked for some big company, he said he would drive a 100 miles to a job...he'd get there and they'd tell him...you need to go back to the shop and get this tool we forgot. So then he'd turn around and drive a 100 miles back to the shop, get the tool and drive a 100 miles back to the job site. Said he probably only was actually working a couple hours a day. The rest was all driving. Said he'd put 50,000 miles on that van every year, easy.

 

[Gyro Gearloose]

213000 miles and 13 years in a 2001 Suburban. All it ever needed was oil changes, filters, and an occasional throttle body cleaning.

 

[JeffKeryk]

Hard to say, but back in the '80's I did a tune up on a friend's '60's Falcon with the 6 banger.
Those Autolites were welded into the head. Iron baby!

Nice ride, by the way. Those engines were long runners. 200 cu in maybe?

 

[nthach]

160K on a set of OEM Denso PK20R-11 plugs on a 1991 Lexus LS400. I was shocked at how well it ran. Of course I replaced them with another set of Denso.

 

[UncleDave]

After reading through so many posts, I’m wondering if perhaps I can stretch my plugs out to around 120,000 without issue and then take that intake manifold out, maybe replace the rear coils with new OE coils and maybe do the rear valve cover gasket. Because I don’t want to have to go back in there for a misfire from a coil or a leaking valve cover.

The plugs on my Rx400H looked new at 110K, I feel I could have made 150 easy.

 

[doublebase]

The plugs on my Rx400H looked new at 110K, I feel I could have made 150 easy.

Good to know because I'm not looking forward to doing the plugs on mine.

 

[UncleDave]

Good to know because I'm not looking forward to doing the plugs on mine.

Only reason I bothered was a valve cover gasket leaking, and "since I was in there"

I took this one in at the time but my absolutely superb service writer saved them to discuss.
I dont remember what the electrode was but the

If anyone asks about my relationship with Lexus the best part of it was him, then the product. He took care of me at every turn. (a rare thing these days) I rewarded him with as much business as I could muster for everything.

In retrospect doing them at timing belt time was probably best course for a regular guy, If I ever end up with a 3mzfe based rig again I'll gamble them making it to a 2nd timing belt.

 

[Number_35]

4mm...I don't know what that is in thou.

25.4 mm to the inch ... let's round it off to 25 to make the math easy.

25 mm ~ 1"

2.5 mm ~ 0.1"

0.25 mm ~ 0.01"

Therefore, 1 mm ~ 0.04" (40 thou),
and 4 mm ~ 0.16" (160 thou). Yikes, that's excessive! The plugs I installed a couple of days ago were gapped @ 50 thou (0.050"). Before electronic ignition, the gaps used to be smaller.

("Thou" as in short for thousandths, not as a form of biblical or Olde English address.)

 

[01rangerxl]

My cousin went to just under 300k in his 2004 Silverado 4.8L. He bought the truck around 2006 with under 40k, so the plugs were believed to be original. The engine finally started misfiring in the 290s.

 

[Car guy]

My son is terrible when it comes to taking care of his vehicle other than oil changes. I gave him my Elantra many years ago. I’ve been telling him since 100,000 miles to do the timing belt and plugs. He sold it last week for $500 with 237,000 miles with the original plugs and timing belt.

 

[Electromotive]

I'm one that has fears that plugs will be very hard to remove/ possibly seize after 50,000 or so miles and/or 5 or 6 years in service, so I change them before they come close to being very worn. My three vehicles have plugs that are very easy to change, thankfully.
If I owned a vehicle that had hard to change plugs, I would likely let them go longer before changing.

 

[Just a civilian pilot]

Mine last 110,000 miles and get changed when the Honda maintenance minder says it’s time.

 

[OilReport99]

145k.