What is Galvanneal?

@indigomoth - Just a tip. Bear in mind that if a car has got a rust problem, even if it has been repaired the rust is likely to start again. You can only really slow it down, not stop it, once it gets into the steel. So, make sure that if you are buying a car, they haven't hidden rust repairs, for example behind the tires and underneath the car.

Rust doesn't exactly develop overnight, so if you are diligent in catching damage to the zinc coating before it can get into the underlying metal you should be fine.

Once it's in, however, it's only a matter of time, so avoid buying a car where this is the case.

@irontoenail - Unfortunately, rust can be difficult to prevent when you live by the ocean. The salty, humid air is exactly the right conditions for rust to develop.

Keeping the paint fresh is actually the best thing you can do, rather than putting some kind of conditioner on top of it, which is what I think your father might have been doing. Rust can only really develop in places where the paint has come off the galvanneal. So, after you get dinged by a stone, or anything like that, you have to be diligent and repaint.

The problem is to properly repaint and fill in the damaged galvanneal coating is quite expensive and anything else looks obvious and brings down the value of the car. I suppose you could always do touch ups in between the occasional repaint.

Galvanneal steel is not at all rust proof, as I remember from when I lived by the ocean as a child. No matter what my father did, eventually our cars would start to develop little spots of rust.

Unfortunately, we didn't have a garage at the time, as there wasn't room at the house where we lived, so that probably added to the problem. But, he tried putting all kinds of different mixtures on the car, as I remember.

Of course, I don't remember exactly what the mixtures were, so maybe dad was just easily taken in by people who were selling the car equivalent of snake oil!