Newsprint is normally quite acidic, so you probably wouldn't need to treat it with oxalic before you print, but you will need to size it heavily.
In the US, you can get a pen from Light Impressions called the pH Pen, which effectively indicates the pH balance of the paper with a swipe of the pen. In most cases, a paper that is acidic (yellow) with the pen won't benefit from the pretreatment, but the basic (blue) papers will benefit. You can also see the blue stripe turn yellow in the treatment, so you know the balance has shifted.
If you settle on one or two papers, you don't need the pen, but when experimenting with new papers, it might come in handy to help you determine what the general character of the paper is before you begin trials.