I am compiling a project with Visual Studio 2013 against .NET 4.5 and then checking it again with ILDASM.
What I noticed is that the build in Release still contains method names and variable names, I thought these should be removed in a release-build or do I need an obsfuscator to do that?
As for method names, the compiler doesn't know if your assembly will be used or not in another project, so the preservation of method names is logical. Though variable names can't be used anywhere than in the method where they're defined, I guess it is useful for debugging (be it Debug or Release) and they really take insignificant space.
And my advice, don't use obfuscator, unless your application contains security critical codes (and then, I'd still advise obfuscating just this code, not the other methods). It is way better for debugging and reading exceptions.