Just some guy
Join Date: Jun 2001
Location: SC foothills, USA
AP104 is the platinum version and OK to use IF you have some newer style higher powered ignition. A few people chimed in on the other thread saying that with an older ignition setup you tend to foul platinum plugs. The spark isn't "hot" enough to keep those style electrodes clean. I have seen this myself, iridiums are even more prone to fouling. In the short term with a fairly clean running engine it doesn't matter. Unfortunately our engines don't run terribly clean, even with fancy 1990's cylinder heads on top.
You can bead blast regular spark plugs clean after most kinds of fouling and though they won't be good as new, they'll be OK for most purposes. The same blasting tends to damage iridium and platinum plugs, at least slightly. So when they foul it's best to just discard them. I don't care to throw away spark plugs I spent extra money on after just a month or two, and I have had to. The main purpose of the fancier plugs is extended longevity, so if they give you the opposite you're just throwing money away on them.
All that said, there's nothing wrong with a little experimentation. We don't all have the same engines, live in the same climates, drive the same way, etc, etc. And also just because these type plugs may not work well for us doesn't mean they are the cat's meow in their correct application. The plugs on many newer cars can be so difficult to change it tickles everyone that you don't have to for a hundred thousand miles or so.