I have been running 4-stroke engines for well over twenty years, including OS Surpass, Non-Surpass and Wankels, ENYA and SAITO.
I have NEVER had a plug fail.
I use the plugs that come with the SAITO engines - I have no clue what they are but my SAITO 30 has well over 500 flights with same plug.
I ran it for the most part on Brodak 10/23, 50-50 castor-synthetic and Powermaster 20/20.
Bob Z.