White and rust don't go together... not on cars anyway. Perhaps you should consider a sort of orangey-brown!
I urge everyone to look very closely - and I mean VERY closely, get the step ladders out - for stone chips on the roof. I have just found two more tiny chips with rusty centres, and signs of rust tracking under the paint (it looks like fine threads, or strands of a cobweb; which is why it's sometimes called spidering). If you find any, tackle them *now*, don't delay. Once a rust particle gets under the paint, it brings all of its friends to the party!
I have been given a useful tip from a guy who does stone chips for a living.
First get yourself a touch-in kit from Mazda, they are only about a fiver, they seem to sell a lot for some reason.
Get some strong cheapex reading specs, you will do a better job. (I use +4.0, £3.99 from the supermarket).
Make sure it is absolutely bone dry before you start, if necessary use the wife's hairdryer on its lowest setting to gently warm the area first.
Now tear the corners off a sheet of kitchen roll to make triangles about 70mm, twisted to a fine point, and use that instead of a brush. Pick up a small amount of paint on the pointed end, and 'dot' paint into the chip, slowly working around the edges inwards to the centre. Take your time and avoid the temptation to put too much paint on in one go, but be careful not to leave any pinholes. You may have to return to it after an hour or two and fill in a bit. The more care you take, the less obvious the repair will be.
It works a treat. Shame I have to do it so frequently, though...