I am the 2nd owner of a 2011 RX-8 GT that appears to have been extremely well maintained and had 93K km when I bought it last year. However I didn’t have a maintenance history to go by but for certain the car had upgraded coils and wires along with plugs likely. I drove it 4,500 km this year and premix at about 125:1 using Mystic JASO-FD 2-stroke. I always use the shutdown procedure but likely fail the old Redline a Day method.

Not knowing how many kilometres were on the old plugs, the photo is pretty telling yet the car started fine and idled nice and smooth whether cold or hot. I had a 2005 for 9 years and feel this car is even slightly more powerful although it has a Racing Beat CAT back so maybe it just sounds more powerful! In any case, I’ll definitely pull a few more redlines next season and keep a close eye on the newer plugs as time goes by.

 

Seem about normal. A bit dark maybe, do you spend a lot of time in traffic or doing short trips?
You don't need redlines per se, you just need heavy load for an extended period on occasion to raise the combustion temperature and pressure.
No shutdown procedure necessary unless you gave reason to be afraid of a flood. And even then ..

 

Likely too many short trips with too much photo radar around! I try not to run below 3000 RPM and don’t use 6th gear below 100 kph (60 mph). Working the motor a bit more is tough to do around town but fun on the open road! As for the shutdown procedure, I got in the habit of doing it as my neighbour worked at a Mazda dealership and told me they had plenty of fludded engines come in. Given I store the car for our 5 winter months in southern Ontario, and I have never experienced flooding but don’t want to risk it!

 

The spark plug you posted a picture of looks pretty normal to me. The carbon deposits on the plug are consistent with spark plugs I have pulled out of my RX-8's over the years. I change my spark plugs every 7-10k miles. I'll check them at 5k and then at 7 and reevaluate. Often times I'll clean them and use them until the 10k mile mark and not check them at 7 and they're perfectly fine with normal light carbon deposits. I'm not a redline a day guy either. I do like to floor it when getting on the highway and usually do so starting in 2nd gear. It gives the engine a good workout without abusing it and I feel as though it helps.