White tip of exhaust pipe

[mick taylor]

Just looking at the wife's car exhaust tips today and around the outside edge is a white crud build up, just touch it and off it comes easy as like but very powdery like on my fingers.

The inside of the pipes has never been anything ever than totally clean, never black or any soot by wiping your finger.
Not to mention never uses a drop of oil ever but 1mm on the stick in 10,000KM if that.

She uses Woolworths E10 fuel in it.