My 09S just hit 42K miles.

Cold startup would produce a few misfires. Every once in a while I would get a Check Engine light for multiple misfires. Much like my old MG's, I would feather the throttle a bit until things smoothed out. Low RPM's under load would also produce a few misfires so I would always run in Sport mode around town.

I found the OEM NGK plugs on Amazon for $11.00 each. After I installed them my cold starts smoothed out. Running around town no longer requires the Sport mode. She pretty much runs like the day I bought it.

The plugs I pulled out looked great. No deposits, etc.

So ... if you experience some of the things I mentioned, change your plugs

 

How often should they be replaced on a MINI in general? 60K miles?

Does anybody have a guide as to what should be replaced at each interval? I'm more of a DIY kind of guy and would rather not keep taking my MINI to the stealership.

 

My owners manual states 60k for plug change on my '07 mcs. I'm curious if the '09 mcs w/42k has cleaned or replaced the air filter & what kind of driving conditions is normal for it ?

 

I drive 150 miles round trip to work every day (70 to 80 MPH). I use a DDM air intake system and keep it cleaned and oiled properly. Change my oil every 5000 miles. I also use Chevron fuel system cleaner every 10K and use 93 octane Sunoco gas on most fuel ups.

I like to play with this car when I can. I do not beat on it hard, but drive it like it is supposed to be driven. I manually shift it quite a bit keeping the revs to over 3K before shifting.

I think my manual stated every 50K to change to plugs.

 

What search term did you use? I see plenty of NGKs on Amazon but can't seem to find the correct one.

 

Jeezuz 42k on an 09 holy crap I don't even have that on my 07. If you want your MINI running great and are a performance freak every 10 to 15k would be a good idea but its not really worth it unless you rack your car a lot.

 

Search for the number that is on the plug - Mine was ILZKBR7A-8G

I have found out that there were some defective plugs out there. I have not chaged these out as of 56K and it is still running great. Finally able to put gas in with Techron since I have moved to Georgia.

Don't have to drive so far to work either anymore.

 

I have an 2008 R56 with JCW tuning kit with 46500 miles. My commute is about 58 a day plus it is the primary car driven on the weekends.

I change the oil every 75000 miles, Seafoam every 5000. My plugs are due to be changed at around 56,000 [every 2nd oil change per the recomended interval with the JCW kit]. I bought the extended maintenace plan which will pay itself and maybe even get some od the cost back.[but that is another thread]

 

I hope that a typo