Are these spark plugs new or used?
Spark plug wear is judged by electrode erosion, gap widening, and deposit buildup rather than just clean appearance. Telling a new plug from a high-mileage one requires checking for rounded center electrodes and heavy carbon or ash fouling, which prevents proper ignition and misfires.
What the numbers show
Counted from the threads quoted below. How we count
- The most recent one is from October 2026.
- This comes up 13.9× more often in r/AskMechanics than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Replacing them anyway since they are already removed2 people mentionedDid this help you?
- 2Visual inspection of the spark plugsDid this help you?
- 3asking mechanics online for adviceDid this help you?
- 4replacing the spark plugs based on appearanceDid this help you?
- 5Asking online mechanics communities to inspect photos of removed partsDid this help you?
- 6Replacing spark plugs based on mileage milestones rather than visual inspectionDid this help you?
- 7Pulling out the spark plugs to manually inspect the gap and conditionDid this help you?
- 8Attempting to replace the valve cover gasket independentlyDid this help you?
- 9Inspecting the exact location of the oil on the spark plugs to determine severityDid this help you?
- 10Replacing only the single spark plug for nowDid this help you?
- 11Consulting online forums or friends for opinions before starting major repairsDid this help you?
- 12Replacing valve cover gaskets and spark plug tube gasketsDid this help you?
- 13Cleaning them up with a wire brush to reuse themDid this help you?
- 14Relying on mileage service intervals rather than visual inspectionDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“Honestly i dont care to replace them just curious if they are in need of replacement or if there is no reason too.”source ↗
“these spark plugs look brand new or used (say 30,000 mileage)?”source ↗
“this spark good or bad?? pls help i need explain😀😀”source ↗
“No i can feel the burb is kinda sluggish and my mpgs have dropped for-sure and with the price of fuel, thats why i pulled them.”source ↗
“the first plug pulled had this tacky residue on its threads. I just replaced this 1 for now. A friend said it looked like oil from the valve cover leaked in. I have my reservations because all but the threads are bone dry. I would like you alls opinion before I invest in replacing the valve cover gaskets which will be a PITA on this engine.”source ↗
“If it was on the tips and not in the spark plug tubes, and judging by the amount of gunk in this cylinder you’re going to be rebuilding your engine; not replacing a valve cover gasket.”source ↗
“Changed spark plugs on skyactiv 2.5 g and one of the spark plug has oil on it,should I be worried.”source ↗
“I replaced the plugs because of the recommended interval. Can anything be told from the condition of the removed plugs?”source ↗
“I don't know how to really tell what worn spark plugs look like, and I'm just curious if these look bad or not.”source ↗
“New ones were installed and we’re going to be installed regardless but I was just curious if it was really needed.”source ↗
“All the spark plugs had oil on top of them, so I'm pretty sure it just needs a valve cover gasket.”source ↗
“i would have cleaned them up with a wire brush and put them back in. How many miles did they have on them?”source ↗