yum - how to cleanup downloaded yum cache

[David Timms]

I've tried to find a way to clean up all the old headers and downloaded 
RPMs that accumulate in /var/cache/yum

There is a yum clean all:
CLEAN OPTIONS
The following are the ways which you can invoke yum in clean mode. Note
that  "all  files"  in the commands below means "all files in currently
enabled repositories".  If you want to  also  clean  any  (temporarily)
disabled repositories you need to use --enablerepo=’*’ option.

yum clean packages
Eliminate  any cached packages from the system.  Note that pack-
ages are not automatically deleted after they are downloaded.

yum clean headers
Eliminate all of the header files which yum uses for  dependency
resolution.
yum clean all
Runs yum clean packages and yum clean headers as above.

Notice that this says "all" or "any" in the descriptions; this is 
definitely not what I want to happen.

What I want is to erase (the thousands of) superseded header files that 
are no longer current, leaving with only the current headers from repo, 
and also delete the superseded rpm files (probably another 1000-2000 
files and 1.5 to 2 GB of data), ie if the rpm is not in the current repo 
file list, then delete it for each repo.

I also installed yum-utils, but the tools I noticed (yum....) don't seem 
to fit the requirement either.

Any know how to do this ?

Thanks, DaveT.