Western Canada here, Northern Alberta. I had a small amount of rust above the rear left wheel well. Just grinded it out, filled with fiberglass, smoothed with bondo, and repainted. Good as new. :)
1991 LS 400 =D
No salt on the roads here.. lots of snow thou. :)
I did the same thing on my chicagoan ls400! the rust was in the same place. weird.
Places to look out for rust,
1, underbody
2 rear wheel wells
3 front fenders
I have a small rust "bubble" under the paint developing in the same place, above the driver side rear too, and nowhere else! Strange.