Originally Posted By: NMBurb02
Originally Posted By: martinq
Originally Posted By: PandaBear
... it shows that sparks are generated at the "edge" of the electrode and not the center; that's why fresh plugs with sharp edges gives more "performance".
This is a good reason to go with platinum tipped plugs even if it's only one electrode. Small/sharp area that doesn't wear.
If you want a small sharp area that doesn't wear, you want iridiums. Both cars in my signature came with iridium plugs and the manual doesn't call for replacement until 100k miles due to their resistance to erosion. I recently put new plugs in the GP and most of the plugs looked good, despite it appearing that they were all original and had therefore been in the engine for more than 131k miles (bought at 131k). The only reason I found out that they needed to be replaced and were most likely the originals is that I got a misfire code.
Iridium may wear better than platinum, and might be a good application for a car with a bleep of a rear cylinder bank access, but they cost more and the car makers use them for "long life" purposes (and to meet certain emissions requirements for service life,) not because they work any better. In a car where it's easy to get to the plugs, and you know how to do it yourself, a single electrode platinum is OK. Plus, taking the plugs OUT once and a while means they are less likely to be frozen in when you DO need to change them.
Originally Posted By: martinq
Originally Posted By: PandaBear
... it shows that sparks are generated at the "edge" of the electrode and not the center; that's why fresh plugs with sharp edges gives more "performance".
This is a good reason to go with platinum tipped plugs even if it's only one electrode. Small/sharp area that doesn't wear.
If you want a small sharp area that doesn't wear, you want iridiums. Both cars in my signature came with iridium plugs and the manual doesn't call for replacement until 100k miles due to their resistance to erosion. I recently put new plugs in the GP and most of the plugs looked good, despite it appearing that they were all original and had therefore been in the engine for more than 131k miles (bought at 131k). The only reason I found out that they needed to be replaced and were most likely the originals is that I got a misfire code.
Iridium may wear better than platinum, and might be a good application for a car with a bleep of a rear cylinder bank access, but they cost more and the car makers use them for "long life" purposes (and to meet certain emissions requirements for service life,) not because they work any better. In a car where it's easy to get to the plugs, and you know how to do it yourself, a single electrode platinum is OK. Plus, taking the plugs OUT once and a while means they are less likely to be frozen in when you DO need to change them.
