06 XC70 - Recommended spark plug frequency?

[MoVolvos]

I’m running the copper Volvo OEM plugs on the entire fleet, replace every 25-30k miles. It’s cheaper with Fast Change Plugs, too. I don’t like any steel plug sitting in an aluminum head for 5 years.

If you can wait until September I can bring some up? Send me part number and I’ll check the Colonial price

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Going down the copper colored road also. Research indicates copper still the best conductor for spark plugs so the last couple sets purchased have been copper for a few different makes including Volvos. So much cheaper and with the few miles driven each year should last awhile. That being said the last set of Iridium for the 03 Odyssey has been excellent going on 80 to 90K and van is at 249K. Was a night and day difference in engine performance after changing. Probably should change it again soon however.
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[scot850]

Abscate makes a good point on leaving sparkplugs in an alloy head for many years. That was why I let the dealer deal with replacing the iridium plugs in my then 15 year old 4Runner. It was way short of the 120000 mile recommendation (it has only hit that now at 21!), but I was worried about the issue f the plugs getting welded to the head. I will likely replace them again in a couple of years possibly (8 years) when it may only be at 40 or 50kkm (25-30 k miles) again due to time rather than mileage. They are cheap enough Denso Iridium plugs compared with the Volvo plugs. And that is for 8 not 5!!

I watched something recently that stated that more modern cars have plugs fitted with an anti-seize already in the plug threads. I will continue to use thread ease!

Neil.