2000 V70 2.4 Perennial Question: Which Spark Plugs to use?

[cn90]

Time for an update on NGK BKR6EIX Iridum plug, $7/each at local parts store...
BTW, NGK Iridium plug is probably better than Denso brand Iridium plug.
If you decide to use Iridium, stick to NGK!

I installed these Iridium plugs in my 1998 BMW 528i in Aug 2012, the BMW runs very smoothly and the engine loves this plug, on highway I get 30 mpg.

Last month I installed the same Iridium plug in my newly acquired 2005 XC90 2.5T, the engine runs very smooth, much better than the factory plug.

One thing about Iridium spark plugs that people may not realize: although all spark plugs deteriorate with time/mileage, the standard copper plug ($2/each) deteriorates faster and one needs to re-gap it every 20K-25K or so.

The Iridium plugs that I pulled from some engines with 60K-80K, the gap was unchanged!

The point is: if you use Iridium plugs, the upfront cost is higher (than copper plugs), but the fuel mileage savings could be substantial over the years making this upfront cost a good investment.

Example:
- Iridium plug $7/each
- Copper plug $2/each
Difference is $5 x qty 5 = $25 upfront cost difference.

Filling a gas tank these days is about $50+++.

So $25 upfront cost is nothing when comparing with thousands of dollars we spend on fuel every year.

So Iridium is the ticket for me...