I use mini cooper for once or twice weekly drive. The spark plugs of the mini cooper R56 goes bad on this moderate use every year!

What is the reason for this? I obtain genuine spark plugs and the car starts wobbling and sluggish in picking up acceleration, in about an year telling me that spark plugs needs to be changed.

I have to press full throttle so engine revs up fast eliminating the wobble and sluggish acceleration.

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  • 1
    Welcome to the site? What do you mean by go bad? There are many things that can go wrong with spark plugs and they point to completely different problems. Can you post a couple of pictures of the plugs? If not there's no way we can help you.
    – GdD
    Jul 24, 2021 at 13:53
  • Also, what type of sparkplugs are you using (brand/type/model)? I don't remember off the top of my head which type you should be using, but if you're using a copper plug where iridium is called for, this could be your reason. Also, what type of fuel do you use (RON or Octane level)? Is this the "S" or just the plain Jane Cooper? Jul 24, 2021 at 13:57
  • @Pᴀᴜʟsᴛᴇʀ2 I have updated the picture of the plugs. Its BERU plugs. I am using 91 octane, the model is plain Cooper not S. Let me get more info based on your comments and add them here. Thanks.
    – user0193
    Jul 24, 2021 at 14:18
  • 2
    This is my "suggestion" so leaving it here in the comments. You need a hotter plug. Definitely one range, but possibly two ranges hotter. The plugs should look tan in color, but they are covered in carbon buildup. Secondly, I'd get a better plug. While the OEM specs may call for a copper plug, an iridium (or platinum at least) will give you better longevity. I can't tell what brand those are. My suggestion is to get amore main brand one, such as NGK or Denso. Even ACDelco & Motorcraft are good plugs. Again, these are just suggestions. Jul 24, 2021 at 16:00
  • @Pᴀᴜʟsᴛᴇʀ2 thanks a lot for these suggestions, the carbon soot forming on the plugs makes me wonder if the head gasket needs changing as well, perhaps the engine is sipping oil into the cylinders hence such buildup, or perhaps thats something normal and can be eliminated by having iridium or platinum plug?
    – user0193
    Jul 24, 2021 at 17:32

2 Answers 2


Per comments , fuel is leaded ; That opens a Pandora's box of problems. Tetraethyl lead was accompanied with bromine to scavenge the lead compounds so they would not foul plugs, etc, so fast. Also , I expect any location allowing lead today also has high levels of sulfur permitted. There is also damage to the plugs where you can't see ; deposits between the porcelain and the steel body are leaking some ignition spark energy giving a weak ignition spark. Cleaning the plugs is only marginal help. Using leaded gas , I think your best option is do what we did in the old days, get new plugs every year. I am not certain but I don't think platinum plugs is a solution although they may be better

  • Too late now, but I was going to say , I haven't seen plugs that bad since the days of lead. The Amoco lab I worked at analyzed hundreds of spark plug deposits and failures , not for the public , but for trucking companies the bought brazillions of gallons of gasoline. from Amoco. Jul 24, 2021 at 21:36
  • This makes sense. Perhaps a good perspective as i didnt know if my spark plugs were that bad.
    – user0193
    Jul 25, 2021 at 12:23

It's always recommended to use spark plugs listed in owner's manuals. To use other than factory spark plugs makes you the Beta tester requiring knowledge of plug type, heat range, plug gap setting, etc. If you are using OEM spark plugs and wear or fouling occurs then this isn't a plug issue. Although most vehicles require less maintenance, replacing spark plugs, cleaning throttle bodies, replacing air and oil filters are still maintenance chores either a diyer performs or pays a dealer or repair shop to perform. Owner's manuals always suggest maintenance intervals to ensure optimum performance from our vehicles. Ignoring or forgetting maintenance introduces problems either sneaking up slowly or immediately. Servicing also allows one to see if any unusual wear occurs like a ruptured rubber hose or leaking fluid.

Using your car only once or twice a week would be considered light duty use, not anywhere near moderate use like daily driving. Severe use would be Ubering or delivering pizzas/fast food daily.

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