Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Good Spark Plugs

I have a 2002 Nissan Altima, 4 cylinder with the original platinum plugs( 9 years). Car has 67K on it since new. Do these plugs need to changed? car starts and goes with no problem.

Platinum plugs are usually good for only about 60k miles. They may be fine for another 10-20k miles. Personally I’d change them. You don’t want them failing in the middle of winter when it’s -20 and you’re 10 miles from the nearest town.

I have a 2002 Chrysler Town & Country that I bought new. It has platinum plugs which the manufacturer said was good for 100k miles. I changed them @ 110k even thought the engine was running perfectly. Installed new set and @ 146k miles runs like a top.

Yes, they can very well last that long, however, one good reason to change them more often than 100K is that the plug will bond with the head, and may cause damage coming out. Personally, I’d rather spend a few $$ on plugs than re-work the head.


“however, one good reason to change them more often than 100K is that the plug will bond with the head, and may cause damage coming out.”

That one is worth repeating.

I’m one who believes that a good set of plugs is an inexpensive way to keep an engine running well. 67,000 miles is perfectly good service from the platinum OEM plugs. I’d change them. Others have detailed good reasons to do so. I’d add that while the plugs may last 100,000 miles, that doesn’t mean they’ll be firing as reliably or cleanly as they did when new, and that can cause things like carbon deposits and reduced gas mileage.

And that can cause the Check Engine light to come on because of a misfire.


Check your owners manual. you can go by that. There are two different types of platinum plugs, single tip and double tip. They look identical except on close inspection. A single platinum tip uses platinum on the center electrode only. A double platinum has a platinum center electrode and a platinum pad on the ground electrode as well.

The single platinum plugs should be changed at 30-40k miles as the ground electrode erodes away. The double platinum are good for 100k or more. Don;t worry about them bonding to the head. After the initial problems with this, the plug manufacturers started plating the threads with an anti-seize plating. They will come out surprisingly easy. I’ve pulled them at 120k and they came out with no resistance, it was like they were put in yesterday.

If You Like Platinums, You’ll Love Iridiums, Standard Equipment In My Bonneville. I Believe They’d Last The Lifetime Of The Car If I’d Let Them.

I change mine every 50K. Changing them on my car at least makes absolutely no difference w/regard to how the engine runs, but I do notice some minor build up on the tips on inspection of the old plugs. I think the car would continue to run fine at 100K or even 150K. The main reason I change them is what was mentioned earlier: If you leave plugs in too long it can become difficult to get them out without damaging the threads (where the plugs screw into the engine). If that happens, its a big job to fix, so it is best to avoid if possible.

I’m not sure what the expert mechanics do, but I always spread a tiny dab of moly lube on the spark plug threads when I install new plugs in order to help prevent this problem, and have never had a problem of thread damage when removing the plugs every 50K.

My 05 4runner and wifes 08 Lexus have iridium plugs. I change them at 50k miles. They are probably still good at 50k, but I don’t want to be trying to get a plug out that’s been in the engine for 100k miles.

The tips on platinum plugs don’t wear down much at all. Leaving them in a long time can be a problem when you go to take them out eventually. Other parts of the plug deteriorate, mainly the gasket at the base where the ceramic meets the metal base. When the gasket goes bad, moisture will affect the plug causing the electricity to arc to base (rather than the tip) and that is a mis-fire.

Those plugs have been in there 10 years. They don’t owe you anything. I’d change them, but you can leave them in - it is your car and your call.