Note: Allpar does not take responsibility for the veracity of any information or opinions here, does not claim expertise, and is not responsible for any consequences. Please proceed at your own risk.
Mike Nakagawa summarized a long discussion:
It seems that, like many issues, there are two camps regarding Bosch Platinum Plugs.
One set of people says they work great and cleared up a lot of hard to fix problems, idling, etc.
The other set of people point to all the incidents of mangled plugs and indicate no noticeable improvement when they used them.
It seems that the problem cases have generally been with high performance engines, and the 'works great' group tend to be on, um, 'less aggressive' engine/driver combinations. (?)
I recall seeing that Bosch platinums were supposed to operate at a lower voltage. If that fixed a problem, then perhaps there was something else wrong with the ignition system, perhaps wires, and perhaps fixing the other problem would allow 'normal'/other plugs to work just fine. Performance engines tend to be more cared for and perhaps don't get to the point where low voltage plugs would show any sort of improvement. In fact, they tend to need higher spark voltages, so...
Performance engines tend to work harder, and perhaps the Bosch Platinums aren't up for the additional stress. But if you don't stress the engine, e.g. no turbo, no WOT to redline, etc., perhaps they work fine, or better for non-aggressive driving.
I'm hoping that explains the discrepancy, and that we can put this controversy over Bosch Platinum plugs behind us.
Incidentally, Bosch also makes the 'Super' tri-electrode plug. This would seem to counter the ability to index the plugs, so perhaps we see another example of Bosch plugs not designed for the performance market. (pre-emptive disclaimer: this is not to say that they don't make *any* performance plugs)
Hoping this is the last I see on this issue (for a while anyway)
p.s. my $0.02. I've been using BPPs. They warm up quickly in winter. I haven't seen catastrophic failure. I don't push my car hard for very long, and not very often (any more). After reading all the disaster stories (on this list and on the web, primarily dealing with turbocars), I'm deciding on my next set for when I change the cap, rotor, and wires. Perhaps NGK?
All Mopar Car and Truck News