Multiple electrodes provide many paths of least resistance instead of just one.

Think of each electrode being North , South , East and West.
As one wears the spark changes to the next electrode with the path of least resistance.
For example. If the North electrode is wearing and the South electrode is next in line to have the optimum gap the the spark jumps from the centre to the South in place of the North.
As the South electrode wears the spark then goes to the next least worn electrode in line say East and so on.
There IS only one spark but having multiple electrodes allows the gap to stay closer to optimum for a longer period of time hence the longer intervals between replacements.

Cheers , Pete.

I've tried bosch-4 plat. plugs in a Honda before that was otherwise tuned-up, and it ran terribly. Switched back to the OEM NGK v-power plugs, and it ran fine.

Any Honda I've bought has always got better MPG with the correct NGK plugs than platinums. I have gone with irridium NGKs once, which did yield the same MPG as the v-powers, and if you are going for a long period of not changing plugs, I would get those instead.

But with a civic, it's so easy to replace the plugs. Just make sure to use anti-sieze on the threads of the plugs and dialectic grease on the wires. I replace my NGK v-power plugs yearly (20k mile interval) and doing that has always gave me a smooth-running car. IN one year they are always rouned where they were pointed and the gap has always increased. But for me $8 on plugs a year and 10 minutes to replace them is always worth it.

Bosch plugs do multiple sparks by virtue of the fact that they are high resistance, thus dribble your spark energy out slowly. This makes them good for some turbo engines 'coz if the spark gets "blown out" there's still charge in the wires for it to re-establish itself. However, they will make weak plug wires etc flash over 'coz the spark tries to find an easier route. Many are the cars that don't seem to like them, Fords and Dodges seem to be in this category. I believe this is because they have relatively high ignition output from the factory, in the 30KV plus range which is reckoned to be HEI when upgrading. Additionally, if you read up about the benefits of plug indexing, and then look at a Bosch +4... you'll notice that whatever you do, it shrouds the spark.

As pointed out, the mileage interval possible on the +4s is partly due to the fact that they have 4x more "edge" for the spark to start from, and also because lower ignition energy density from the higher resistance means that gap erosion is less severe.

Platinum is a good catalyst for many reactions, this makes it good in a motor right? Not really, it will decompose ethanol vapor into water and CO2 while glowing red, it will also catalyze H2 into H2O and glow red... This often happens BEFORE the correct ignition point in a hot motor, thus you get preignition issues. Therefore, platinum plugs may run poorly in combo with E10 or higher, or with a HHO or other hydrogen assist system.

lol theyve had multi electrode plugs for a very very long time (pulled a dual electrode spark plug out of my 1929 model A engine)

everyone ive heard that use the bosh ones have had issues later on or doesnt seem to make a difference...

i just stick to OEM and dont worry about em.

CivicRick,
I was told by a parts person and my toyota mechanic that multi-electrode plugs do not make any difference. I am running a 95 toyota v6. Different make and engine than yours, but, you can increase performance many other ways. If you can see a big difference between using cheap plugs versus the "best" on the market, you may find that something else is really amiss like bad wires or bad Oxy/fuel mixture before combustion. Make sure your main systems, compression, and your plug wires are all good before you make a plug change. When you change the plugs last, any good/bad differences should be attributable to the plugs and nothing else. Also, I have returned plugs before without any problems with my supplier. Ask before you buy, you may be able to test out a few theories before you stick with a solution.