[Fox530]

Hi guys,

I've just picked up a 335i M Sport. Very pleased with it though I noticed the high gloss shadowline is looking quite tarnished - I notice this seems to be a very common issue on E92's.

The car is still under the BMW new car warranty - is this sort of thing covered? Any experiences?

Thanks!

[toxicnerve]

When you say tarnished does it looks "spotty" with polarised effect like oil on water? If so give it a wash and then a coat of wax over the top. That seems to stop this effect.

If it's something else then it might be buggered.

I had mine replaced under warranty due to it bubbling.

EDIT:

'grats on the new motor

[Fox530]

Yup - it just looks all oily

Thanks!

[CarAbuser]

Super Resin Polish. Give it some elbow grease and it'll come out perfect again.

I was under the impression that it was caused by wax in the first place, mainly that pour on style wax dealers use.

[toxicnerve]

I've found it happens after washing and drying if no wax is applied.

If waxed after washing (using a paste-wax) it appears to keep that oily film type appearance away.

I have no idea why though, surely the paint is not oxidising or anything?

[Shadow]

Originally Posted by toxicnerve

I've found it happens after washing and drying if no wax is applied.

If waxed after washing (using a paste-wax) it appears to keep that oily film type appearance away.

I have no idea why though, surely the paint is not oxidising or anything?

Mine does it too - especially if I use the local quick-and-dirty jetwash. I think the spray-wax they use makes it worse.

As to what is happening, it is the same physical process that causes colourful effects with thin films of oil on water, or soap bubbles. Light is reflecting off the actual trim surface, and at different points passes through a different thickness of wax/oil/soap contamination. This causes interference at a specific wavelength of light, which we see as colours. It only takes a tiny difference to cause the effect, as the wavelength of visible light is so small (500-700 nanometres). Waxing after washing is building up a layer which is too thick to affect light in the visible range.

That suggests a way to stop it is to clean the surface of all contaminents with a safe solvent that will strip wax & oils - like iso-propyl alchohol on a microfibre - then maybe protect with a very small amount of wax.

This is why soap bubbles are coloured (and why thick or very thin soap bubbles lose that colour). Oxide layers on bare metal surfaces can do this too - it's how you make the colourful titanium jewellery for example.