White corrosion on bolts near tweeter speaker?

[ansys]

Hi all, the two bolts under the tweeter speakers on the drivers door have a bit of "white rust" corrosion. I'm no electronics expert, should I be concerned about grounding issues? I've had the car for 6 years without problems to date and this is the first time I've taken the drivers door apart to see this. Also looks like some white powdery stuff is being sprayed toward the back of the door card? What's going on?

Some things to note:
I don't notice this corrosion on the passenger door.

Years back I had a cut wire in the passenger door harness that must've been shorting out as the stereo was cutting in/ out. It's since been fixed

The plastic sheet covering is missing on the door

[GDII]

That will be zinc oxide from water getting on the bolts a long time ago. The tweeter is earthed through its own wires so no need to worry about that.

Not sure what the what stuff is on the door card.

[ansys]

Thanks, so I presume that it's just the same benign thing going on with my left front strut tower bolts and nearby bracketry etc? Right side ones look fine in comparison. It's just strange to me that it would happen on one side and not the other.

[Benckj]

The corrosion occurred on zinc coated steel materials when it comes in contact with hydrogen & oxygen forming zinc hydroxide. Generally not an issue but sign of trapped water in area of warm conditions.

[GDII]

All the bolts and brackets are coat with zinc, a protection layer as it is far more stable than bare steel. However it will still corrode give the right conditions. It might look a bit funky but the layer on top is quite strong unless exposed to the water and salts for too long.

In some situations an oxide layer is actually an advantage to protection even though oxide such as rust on steel is normally bad.
Bare aluminium boats. Aluminium oxide is actually quite hard and can protect the aluminium underneath. It's not often you actually see true aluminium as it reacts with air very quickly so normally you are seeing an oxide layer. Anodised aluminium is an oxide layer that has a protection coating to seal the pours of the oxide layer to protect it.
Stainless steel. The stainless component of stainless steel is chromium oxide. It creates a hard corrosion resistant layer that protects the steel/iron component of the metal. It isn't fully resistant to corrosion hence the 'less' component of the word but it's far better than steel.

Just some things to think about. The SW body was dipped in a zinc layer before paint which is why thy are quite good at not rusting vs the older AW which was not. Sure SWs rust mostly from damage or in countries that use road salts but in NZ they are generally rust free but the AWs are quite bad for it.

[ansys]

thanks for all the feedback guys!