It is easy to get dazzled by marketing campaigns with products that can handle the toughest environment when it comes to corrosivity (C5). Many believe these products have to be the best and that you really get quality products in place if you were to mount these.
What many people do not know, is that to technically be able to say that a product fulfills C5, the standard only demands 2 years of testing. If the product is approved after these 2 years, you can brand the product with the C5 standard. This becomes a bit irrelevant and meaningless, unless you are pleased with the product lasting for only 2 years of course.
First you have to figure out what the environmental preconditions are, which corrosivity class, you are about to mount a product in (there are tables available with examples of environments in C1 to C5) and then check how long the warranty period is in that particular environment. It happens that technical data sheets state one thing, but when you check the warranty, it can actually exclude the environment that is used in the marketing campaign. What then happens is that you get a crash between the standard (2 years) and the warranties, where anything between 10-50 years can apply.