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Hey guys,
So I just picked up my new wifey (2012 is350 AWD) with 24mi and am now at around 600. I pretty much followed breakin procedure with the exception of some fairly hard, non-WOT, acceleration (I'm only human). I broke it in primarily on I-70 from Denver to Aspen and back which is a very mountainous drive, therefore never keeping the RPM's consistent. I also kept it under 80 with an average speed of probably 65-70. In addition, I always take it easy until she's up to running temperature.

I'm now noticing that there seems to be significantly more carbon buildup in the passenger side tailpipe compared to the drivers side. I see no oil level changes, smell no burning oil, and she purrs like a lion.

Should I be concerned with the carbon? All the opinions I've come across say that the carbon is normal etc.. but after owning a few Hondas I'm fairly familiar with the signs of oil consumption and if I've done or am about to do some damage like cylinder scoring I'd definitely like a heads up.
Thanks!
 

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No, actually the carbon deposits on your exhaust is completely normal and should start to go away and get better after 5K miles. You will also notice a loss of oil as well while the new engine is running. Some new owners may have other explanations, such as rich fuel mixture (air-to-fuel ratio less than 14.7:1, not enough air to ignite 100% of injected gasoline). So, I know its pretty normal for this to occur and should get better over time. Hopefully you're not blowing black smoke continuously on the extreme side. Just make sure you change the oil at the proper intervals, monitor its level, and use good pump gas. Also, contrary to popular belief, the break in for new engines is to run them and run them hard without running it easy. Despite anything the dealer may have mentioned. Take a look at this article, you may find it interesting like I did. This guy built 100's of engines and explains break in with a better approach which most aren't aware of, but makes more sense.

Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power
 

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By the way, you can clean the tailpipe with an automotive polishing compound, or use mothers mag chrome polish and cleaner, works great. After 5K miles or so, I would keep an eye on it. Really it should only get better from here on out.
 
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