100K Miles....keeping original plugs for now

[floridafitz]

The new-to-me 2008 Envoy is approaching 100,000 miles. I purchased it from the dealer who took in in trade. Original owner purchased from same dealer and has a history of regular service. I've done a visual inspection as well as I can of the plug wires and they look good. No misfires, codes or any telltale signs of plug failure. At this point don't plan to change out the Iridium tipped plugs at the recommended 100K. Anyone want to weigh in pro or con? Did the 100k tranny service drain, filter and fill. Fluid looks good. Anything else you would do at this mileage. Thanks for helping me out as I get familiar with the 5.3.

 

[Tiggerr]

I'd change them myself... and all fluids...diffs/tcase,coolant etc

 

[Mounce]

I would also change them. Would wish they'd been changed if you're on a trip and one decided to die.

 

[christo829]

I did mine (on my 4.2) at roughly 100k mi, and while they were in overall good shape, the center electrodes were definitely eroded. I wasn't having any issues with them either, just trying to keep in the ballpark on suggested maintenance.

You could always just pull one and see what shape it's in. If erosion has altered the gap enough, it would be worth changing them.

Cheers-

Chris

 

[Reprise]

Also, if the ECM is able to adjust as they wear (it can do this for a dirty throttle body for example), then things might feel 'fine' to you - but unless you look at the electrode, you won't know that the plug is technically shot.

I wouldn't expect a lot of additional life in the plugs at 100K, so I'd replace them, to be honest. And the wires as well - same applies - they could look fine on the outside, but one or more could be marginal or about to go out entirely.

 

[C-ya]

I'd change them myself... and all fluids...diffs/tcase,coolant etc

Transfer case is important if 4WD. It should be done every 50K miles. Not sure how many miles were on it when you bought it but it would be interesting to know if the dealer changed it @ 50K.

I second the plugs and wires change. I did mine myself. Not terribly difficult once I got #2 done. Pull the right front wheel and get 4, 6, and 8 through the wheel well. Driver's side (odds) are easy.