As many of you know, I maintain a 4 stroke discussion group. 
This interesting question from Hube Start prompted me to share it here.

Hube wrote:

"Subject: Saito 56 Plug?
Bob,
Someone recently discussed a comparison between OS and Saito plugs
for the Saito, and I don't recall the recommendation. One was longer
lasting and didn't burn out as quickly. Which one is considered best?

Hube"

I answered :
"Hi, Hube - always good to hear from you. 

Plugs on 4 stroke engines will always provide for interesting discussion.   

Although 95% of my 4 stroke experience is with the smaller engines (.40 and under), I have NEVER had a plug failure.

My first SAITO .30 still has its original plug, with well over 500 flights.

For over 10 years, I have been experimenting using different fuels (5 to 20% nitro, all castor, all synthetic, different blends of both), props, run speed and plugs.
I have flown in temperature ranging from below freezing to well over 90 degrees.
I have tried EVERY brand of 4 stroke plug on the market.

Bottom line - As far as I'm concerned, there is absolutely NO DIFFERENCE in plugs.
Many have claimed that the OS 4S plug is superior but I have not found this to be the case. An excellent plug, yes, but just as good as the others I've tested.

Now, many of you who fly with the larger engines will, I'm sure, have different results so let's hear from you.

I do not know if the plugs that come with SAITOs are their own brand or what but they are excellent.

Comments??   

Bob Z."