Well, I'm back to report on the results of my experiment with installing Bosch Platinum Ir Fusion spark plugs (with 4 ground electrodes) in my 2003 Protege DX, 2.0, DOHC.

I drove about 5,000 miles on these plugs before deciding to install a set of NGK BKR6E-11 plugs, which are the cold OEM plugs specified for my vehicle in the manual (actual OEM were NGK BKR5E-11). With the Bosch plugs, I noticed two things which I think were related to the plugs. The engine pinged during hard acceleration and the gas mileage with these plugs has been disappointing. Since installing the NGKs, the pinging has pretty much disappeared. We shall see what happens with the mileage.

I read some place that the reason the OEM plugs generally work the best is that vehicles are engineered and tested with the OEM plugs and that OEM plugs are engineered for relatively small number of models, so they have characteristics that are pretty much ideal for the vehicles for which they are specified. Many aftermarket plugs are not that specific in the models they are specified for. For example, I read somewhere that Bosch makes only 7 different Platinum Ir Fusion plugs, so each part number is specified for a very large number models, so the match is generally not as good.

Several members of this forum told me so, I know.
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Nice write-up and good information, protegedon.

Sincethe info/testing you are including could relate to all (Mazda) vehicles, I wonder if you'd mindif I moved this thread, with a reference link from this forum, to the General Tech section?

 

Yeah, by all means go ahead.
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