Spark plug AC DELCO or BERU

At least with double iridium ACDELCO on the c5. It’s 100k intervals.

AC Delco double platinum spark plugs belong in that engine.

use beru plugs rather than Bosch, a lot of Bosch plugs sold for this application has the wrong heat range which can cause misfires.

I use them. Just replaced a set after they'd lasted 90,000 miles, only to rule out a very very tiny misfire count issue I've noticed lately. I might get a coil pack now, but those original plugs surely would have lasted longer (they say they should last for 100k).

I replaced them with AC Delco 14 Platinums, and it seems to be running better.

Just did mine with ac Delco, gapped them in advance and running great!

I ran Beru RS7 plus which are one step colder when I tuned stage 1 and they didn't last at all. Might have been under 10,000 miles. Recently went with NGK plus that APR reccomends for stage 2 and so far so good. No misfires since.

I swapped out the oem plugs for Beru rs7 plugs when I went APR stage 2 at ~3k miles. The car ran well. Fast forward to the present with over 18k miles and is20 swap, and I noticed a few stumbles at idle. Nothing major but I figured I'd change them since APR recommends 10-15k mile intervals (visually the Beru plugs looked fine).

Bought a set of iridium plugs that were wasted after 15k miles. Amazon gave zero fucks. AC Delco gave zero fucks. The scum bags who sold them changed their name and keep selling.

When I got my S60 (2006, T5) the previous owner had some copper AC Delco plugs made to fit an 850 non turbo in it and I wondered why there was very slow engine response.