These are the OEM spark plugs from my 2007 Mazda 3 with 2.3l engine. The plugs have 68k miles with the last 45k miles using 2 cycle oil in the gas at approximately 1oz per 5 gallons, usually a little more. Look pretty good to me, gap was exact across all 4 at .050. I hope this debunks the internet myth that 2 cycle oil in a 4 cycle engine causes fouling or excessive carbon buildup. 2 cycle oil used is Pennzoil Marine XLF synthetic blend. Replaced with NGK IX 4344, LTR5IX-11, gapped to .040.