Platinum plugs are not a gimmick. Long life is the maiin benefit. In automotive service, the platinum plugs last 100,000 miles versus 10 -12000 for regular sparkplugs. This is equal to about 2,500 hours of service for the platinum sparkplug and about 250 hours for the regular sparkplug. With repeated sparks, the metal tip of a sparkplug begins to erode and the tip becomes rounded. Sparks are more easily emitted from sharp tips - not rounded tips. Platinum sparkplugs do not erode nearly as quickly as the regular sparkplug because of the superior materials used in their construction.

Platinum sparkplugs will not prevent the oil or carbon fouling any better than a regular sparkplug. Homeowners keep their lawnmowers around 10 years and about 250 hours. In this case, the regular sparkplug would be fine. The commercial guys who run their mowers 200 hours per month may see benefits with platinum sparkplugs

Here is a link that might be useful: champion sparkplug handbook

Replacing spark plugs now days is over rated IMO. I have several types of equipment that I have never replaced the spark plug and have pulled several out of the trash cleaned them up (including the spark plug) and they run fine.

IMO bottom line is if you've got the skills (if you don't then pay the piper for someone else that does) to remove, inspect, clean, gap, and check for spark you can use spark plugs for very long time (15 plus years and counting for me) Replacing them when the equipment has other problems causing the spark plug to carbon up or foul out is just buying time till the new spark plug does the same thing.

IMO save your money and invest it in oil filters and changes, fuel and air filters, and learning out to clean spark plugs, combustion chambers, carb./fuel system, and air filter which replacing them is money better spent than spark plugs IMO if you haven't ruint the engine already from neglectful pre-ventive maintenance.

IMO replacing stuff that don't need replacing is feel good item. Yep, I replaced the spark plug! my engine and I feel better even though the old one preformed with nice blue spark!

My two cents , I tend to agree with RC's Methology . If it isn't broken don't try fixin it lol . As for Platinum Spark Plug Cores , this is really not something new. I recall back in the late 60's my father who was a mechanic in his younger yrs having replaced a set of Champion Spark Plugs with the conventional copper core and carbon steel centre ground electrode with Bosch Spark Plugs out of the Old 1969 Volkswagon for the Family Farm Tractor (Cockshutt Model 40 1944 vintage). The Old tractor had a little oil blowby which would normally necesitate annual (prior to winter) plug replacement. Thus the change over to Bosch out of curosity ? Anyhow the used bosch plugs lasted over two seasons without a fouling . This surprised Dad who brought the plugs into the scrutiny of a local freind who was a metalurgist . He did his thing and analyized the composition of the plug and advised of the Platinium core design etc , which was a trade secret at the time . You know that German Technology stuff . So to summerize I have used various plugs over 4 decades of repair , racing , toying etc and have come to the conclusion the Manfacturers suggested plug and design are normally sound . I have found that North American Products normally run best with Champions or Motorcraft , Mopar etc were as European often run better with Bosch or Lucas and Nipponese usually seem to prefer NGK . This includes Chansaws , Trimmers , Lawnmowers , Outboards and Motorcycles along with Snowmobiles. Yes there are gimmicks the Iridium design along with the E3 multi Ground Electrode makes sence in theory , and has been put in trial by yours truly on several applications . SO far no failure but again the previous plugs usually last a few yrs also . So as RC has advised sometimes it's just a feel good scenerio . Quite often sparkplug replacment is only masking a more serious problem . Back in the 70's while racing Modifieds we normally chamferred the centre electrode for a better spark kernel and performance from the sparkplug . Normally the plug life was shortened but we were not out for longitivity , just short term performance gains out of our secret octance blends lol .

So Richard there you have it for what it's worth . I tend to agree with RC all things equal , a plugs is a plug some work better than others dependant upon the application and usage.

EWALK
Very interesting story about your Dad, tractor, and bosch platinum plug. So in this particular case, the platinum plug did do better with fouling by at least 2X. Two plus seasons rather than one . . . . So maybe the upside is a lot of longevity, and some increased resistance to fouling???

Better Heat disipation though the core and hotter spark are the selling features . This would assist with break down of any fouling debris around the centre electrode .
I remember back in the day of points and condensor automobile ignition systems if you got 3-4 thousand miles out of set of plugs you were happy . Now a days 20,000 + can be expected isn't electronic ignition and better plug technolgy Great ! :)

20K ? How about 100K.

Ewalk - I thought you guys were on the metric sys? :)

Bay / Rcbe : Roflmbo Your Both Right ! :)

The cross section of the center electrode of a platinum plug is much smaller than on a conventional plug. That is one reason that the platinum plug is less prone to fouling.

JL: In the example plug that I gave the centre electrode was exactly the same cross section only the material composition differed from North American oem design . I recall later designs even used tunsten tip for these reasons , which worked great within 2-stroke applications.
The self cleaning properties were more of heat retention. I agree with todays centre electrode designs this cross section reduction should contribute greatly to carbon fouling reduction as you have indicated.

FWIW, when I bought the GT with 22 HP Briggs twin around 10 years ago, it came with Platinium plugs. As I was going to be busy building a house, barn, root cellar, etc. I bought the service agreement. After a couple of months I noticed it was running rough, called Sears and the guy came out and said I had "bad" plugs.... HUH? He was an old timer and had gone to all the formal schools that Sears used to send their techs to. He simply replaced the platinum with regular and it ran fine. Other than cleaning, gapping, etc. that's all I've ever done.

He commented that not all "platinum plugs are created equal" and that Briggs and Sears (then anyway) used "Platinum" in their advertising as a draw.

Dunno, but IMHO if more money was spent on filters and less on plugs there'd be a lot of machines around a lot longer.

Ev