"

Originally Posted by
Snertz
Anodizing isn't the same as painting, it's an oxide coating which will not chip or peel off. It's done to increase surface durability of the part in terms of corrosion/wear resistance, among other benefits.

All fine and dandy here. If the piece is made out of aluminium, I see no reason why it would be coated. I mean, the entire oil filter housing is non-coated aluminium. Also, not trying to be a prick here, but hard anodizing is not that durable as people think it is.
So I ask again: why coat something that is made out of metal which is constantly submerged in oil? "