Green bolts
 

I occasionally notice bolts that are tinted green. Does anyone know the significance of the green tint?

On airplanes I have seen metal that is corrosion protected with zinc chromate which leaves a green tint, but I haven't noticed any green tinted bolts on the Boxster (but then I am red/green colorblind so I may not notice them). Maybe someone did a repair and used some sort of zinc coated bolts that developed a green tint?

Are you referring to some green on bolt threads ?
If so, that is likely thread locker.

There are green tinted bolts on the Boxster. Here's an example of 2 green tinted bolts used to secure the latch on the underside of my car's rear trunk. I'm guessing that's just some sort of anti rust solution that the bolts are dipped in.
http://i869.photobucket.com/albums/a...ps6ficwxnz.jpg

Most of the green bolts I've seen are on suspension components. I've seen plenty on Volkswagens, just an anti-corrosion coating. :)

I understand these Porsche fasteners use a dip-spun applied zinc-aluminum coating called Dacromet, but the current name for the more environmentally-friendly version of it is called Geomet. The dacromet/geomet coating alone looks kind of matte silvery in appearance, (like aluminum) and you will see this below the green coating, if you ever have "cleaned" grease or oils off your fasteners with an aggressive solvent cleaner, (like brake parts cleaner - or anything with acetone on it, will remove that green coating very quickly.) Solvents will not touch the base Dacromet (aluminum/zinc), however.

Based on the following reference, which says [Porsche-spec'ed geomet] "sealers include ... pigmented ... green for identification purposes", we might infer this solvent-removable green topcoating to be an "Inorganic silicate sealer topcoat", which "provide[s] consistent torque tension values and additional corrosion protection."

http://michiganmetalcoatings.com/yahoo_site_admin/assets/docs/Geomet_Brochure.28482815.pdf

In my experience, it's still a good idea to clean older dacromet fasteners before re-using, and also apply anti-seize, ideally. The commonly available, gray (I think zinc-based) anti-seize seems to play very well with the dacromet fasteners when applied thinly and evenly on the threads, and doing this will also help keep water from corroding aluminum whenever these fasteners are ever threaded directly into aluminum.

I agree with corrosion protection responses, but note my BMW motorcycle has lots of fastener heads with a dab of green paint--factory quality control, tightness verified.