Are Premiere processing "byproduct" files erasable? Need advice!

[Canon GL-2 Guy]

Over the course of the past 7 months or so I have closing on 200 gigs of internal HD space consumed and occupied by what I call aftermath/byproduct or were otherwise created during the post production process using that application.

I'm specifically reffering to:

a) media cache files
b) pro auto save files
c) pro preview files

and the like!

What I don't want to do is to intentionally delete files that I may have to regenerate once more because some of that data points/links to live, open projects that are not completed yet.

So, are any of these "safely" deletable so I can clear some hard drive space?

For example: is there any time lost, damage done or considerations if I did away with the media cache files?

What function do they have & should they be kept?

[Canon GL-2 Guy]

What I don't want to do is inadvertently spend more hours re-rendering each project and tying down my computer.

[edDV]

Yes if you don't intend to re-edit.

Premiere creates temp files when you "render the workspace" for a filter or transition. These are used to make a real time preview. When you encode to an output format and close the project, the temp files can be deleted, but if you reload the project, you will need to re-render the timeline before you can preview again.