I'm in West suburban Chicago, and my '74 is from Oregon 5 years ago, with surface rust but no rust through. Debating on the various treatments, considering a spot sandblaster, then treating with a convertor to soak into the subsurface, then a sealer (POR-15 or something) then paint.

My previous locally sourced Volvos have decayed rapidly. Even 740's seem to lose it at the seams. We have rotten potholed roads with aggressive traffic. Cars get beat up so bad here it's laughable. Ever see a Lexus 400 with a collapsed suspension? I have.

I spend lots of time in Western Michigan, which has also the problem of severely salted potholes and maniacal drivers. I know there are several enthusiasts and one really good RWD mechanic with a big inventory of vehicles.

But the Volvo has gone several years here in probably the worst road salted environment possible, and shows very little worsening. It appears to me that the rust on the Volvo works like anodization and protects the deeper surface, at least to some extent. It may be a steel quality or compound issue.

Any chemists or metallurgists out there know anything about that?