Engine coolant (FL22 type) & Iridium spark change interval

2013 Mazda 5 100k bought at 85k
Manual/Dealer says

  • FL22 first time at120k/10yrs and then every 60k/5 yrs
  • Spark every 75k

Friends tells me that I should change the coolant now (ie 100k/7yrs) - should I wait till 120k. When I did the tranny flush at the dealer, they asked me to wait for the Coolant.

Also, I have no idea whether the previous owner changed the Spark (Iridium-NGK) - it starts fine now. Should I wait till 150k?

Simple , just do what ever makes you feel good . It is never a bad idea to do maintenance early.


Never assume a service was done. If you don’t have proof… receipts… that it WAS done, it is safer to assume it wasn’t done. If you feel better doing a coolant change now, go right ahead. It can’t hurt.

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Spark plugs can stay on the shelf for long time without being used right?
Just in case if I don’t install after purchasing it.

Yes, they don’t age out.

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As I was replacing these iridium plugs on GDI Mazda 3, at prescribed 75K miles, I would have hard time making a visual distinction between the new and old ones probably after a 100 miles, they looked very fresh, although I knew for sure they were not replaced, as the car was purchased long before plugs would be due.

I think you will have hard time trying to guess if yours were replaced 10K miles before or not.

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My iridium plugs were supposed to be replaced at 60k, coming up on 120k now on the original plugs. My coolant calls for 11 years or 110k miles for the first change, then 5 years/60k miles after that. 2014 Subaru Legacy.

Draw out some of your coolant, from the radiator if possible with a coolant tester. If the coolant is the slightest bit cloudy, then replace it soon. If clear (colored clear), then it is still good and you can wait.

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If I was to go through the trouble of pulling the plugs to check them, I’d just put the new ones in.


I called the mechanic at the place I bought the car - he said he is old fashioned and change his fluids early. But said Iridium Spark last 150k or more - he only changed it 150k!

Could u elaborate on it?
What type of coolant tester - link? You do not mean ph testing?

I have an example of when such logic did not work.

My daughter’s prior car was 2007 Nissan Altima, which prescribes iridium plugs to be replaced at 105K miles.

It failed miserably around 98K miles, where one of the plug’ the center electrode was almost completely gone, and an increased gap made for the substantial spike in the high-voltage side, resulting in the rubber boot shot and carbon-tracking, making for the very bad misfire.

Fortunately “dad rescue crew” was only 20 miles away and made it to the store 15 minutes before closing to get new plugs… which helped only partially since carbon track was still causing misfires at idle… finally, few wraps of electric tape temporarily stopped the spark jumping and we were able to use the car for few days until the replacement part showed up.

Personally, I would rather replace plugs at 90K or so if that was on the schedule than have all this midnight hectic rescue mission going under drenching rain and with both me and her needing to get to work next early morning.


Is AcDelco (Iridium) good enough (Factorcy calls for NGK)?

I would rather go for NGK, not that much more expense for the piece of mind.

You might also consider DENSO


It is quite possible the factory knows what it is doing so why not just do that . It isn’t like you are going to replace these real soon.

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Thanks all - there is a lot of nuances here - lot to learn.

They have:

  • Laser Iridium - NGK (factory)
  • Iridium IX - NGK - most popular among buyers (37% cheaper)
  • Professional; Platinum AcDelco cost as much as Iridium IX but on sale

How to test coolant with a multimeter.


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@Tester - awesome link. Quick question:

  • is this to test more of the health of the radiator?
  • I found this video which does 3 level testing on the coolant itself - does these tests complement each other? Watched the video but could not find the brand on shops!

The test indicates the condition of the anti-corrosion additives in the anti-freeze.


Go with the factory plugs. We’ve seen people try to use different plugs on here and come back and post that they’re having problems that resolve when swapping back to the factory plugs


coolant is a lubricant for the waterpump so if you do it early it will prolong the life of the waterpump too . Coolant changes usually dont cost that much either .