2011 Mazda6 4cyl. The manual says to replace every 75k miles. These plugs were installed 4 yrs ago, with 71k miles on the ODO. I changed them out last weekend at 136k miles, so 65k total on plugs. I use the Motorcraft Platinum as that is the OEM. I believe they are the SP411.
No misfires or drive-ability complaints - just figured it was a good time. Is this a good interval, or should I be replacing sooner? These plugs cost around $4/piece, so it isn't very expensive to change them out. I just don't want to change them out needlessly.
Spark Plugs, Old vs. New
Thanks.
edit: While I was changing out the plugs, I took a look down the spark plug hole. The piston tops were black with carbon. Any concerns with this, or is this fairly normal at this age/mileage?
No misfires or drive-ability complaints - just figured it was a good time. Is this a good interval, or should I be replacing sooner? These plugs cost around $4/piece, so it isn't very expensive to change them out. I just don't want to change them out needlessly.
Spark Plugs, Old vs. New
Thanks.
edit: While I was changing out the plugs, I took a look down the spark plug hole. The piston tops were black with carbon. Any concerns with this, or is this fairly normal at this age/mileage?
Last edited: