While the engine was out, I noticed some areas had some rust.  Surface rust, but something to be treated and protected nonetheless. Right side of the engine compartment, under the air cleaner The front edge of the rear crossmember.  It seems as though there is a lip on the front that did not drain moisture away. The crossmember that supports the radiator. On the left side, the shelf that supports the battery.  This area is subject to corrosion  on almost all cars.   I suspect that a new shelf had been welded in at some point.  The 'new' shelf had an indentation that would collect water.  So I drilled some holes for drainage. I did not take many pictures of these areas as I removed the rust and treated the metal, but this photo of the right firewall section is representative.  I degreased the metal, applied some naval jelly rust remover Scrubbed the metal with a wire brush, and treated with Rust-Oleum.  Primer and a finish coat.   At the hardware store, I had a choice of colors of finish coats.  Since the car is a silver metallic, I took silver metallic Rust-Oleum.  But this was a bit too silvery.