You can try chemical cleaners, if the crud is "light" they might help.
Usually, grit is needed to remove the dirt, and oxidized layer(s).
What type/size of grit you need to use depends on how nice you want the metal to look.
Larger/coarser grit will give you a rough and somewhat shiny look, finer grit will give it a more polished, mirror like finish.
A wire wheel on a grinder will "clean" the metal, but give it a rough look, while using metal polish with a cloth wheel will also clean the metal, but leave it much smoother.
All personal choice.
Rob
PS. a sandblaster will work well, and fast, but it won't be shiny...
Waiting for "someday" will leave you on your deathbed wondering why you didn't just rearrange your priorities and enjoy the time you had, instead of waiting for a "better" time to come along...