Originally Posted by BillTex
...Once the skin has oxidized (protective layer of sorts) shouldn't that be the end of any "damage" to the skin?...
i don't think alum surface oxidation has exactly the same protective qualities as it does on iron.
but there are 1000s of units on the road that fit this description and they are doing fine AND look ok to me...
i've seen some with such a uniform light frost/patina, that it would be a sin to shine'em, because they ALREADY look great.
it's somewhat like removing the original finish and 400 years of crud from antique furniture,
old looking BETTER than new is weird (because they weren't shiny then either)
but just because it's oxidizing, doesn't mean the owner isn't continuing to assult the surface, with goofy washings, sprays or slopped on soups...
or that a old unit isn't getting a BEATING from road salts or the atmosphere beyond just surface film...
IF you like how it looks LEAVE it as is.
but i doubt u will get many vendors who vend surface treatments to give blessings to doing nothing...
and when panels get replaced and surface looks piecemeal, a buff and coating with paint or clear or polish is reasonable.