I have a 2009 MCS/manual w/approximately 8K miles. I noticed today that the under-side of the bonnet is starting to show carbon stains; not all over but very noticeable throughout. Granted, the bonnet is white and hides nothing, but does this sound unusual? I run nothing but 93 octane.

Looks and smells just like the junk I used to clean off the upper receiver & bolt of my rifle when I was in military; and that was exposed to direct combustion of the rounds.

Also, any problems using using spray on/rinse off engine cleaner with this car? Thanks...

 

Where would that carbon be coming from? I don't have that problem.

 

It sounds more like you have cosmolene/rust preventative coming out from under the bonnet and it's collecting dust. I get the same thing at the same place on my 08 MCS and yes, it looks a lot like combustion byproducts.

It's not, tho. It's just a combination of road dust and oil. I wipe up the stuff with a plain rag when I check my oil between car washes and use a wet rag and a little car soap during the car wash. It's nothing too serious and should clean up easily.

 

You know, I think you nailed it. I just popped the bonnet again, and it does seem to be emanating from the sections where the edges and seams are. And yes, it does wipe off quite easily - thanks, kind sir.

 

No worries, glad to help out. Watch out for the oil dripping onto the plastic fenders on really hot days; if you leave it sit for a more than a day or two, it can leave a mark. Again, I just wiped the stuff off with a clean rag and never had a problem.