Mass Editing of posts question

[wraggster]

I found a thread over at Vbulletin.com which seems to be something that im looking for basically i want to change all the links in posts on my forum to a new url, replacement variable manager does work mostly but because i grab feeds from our news forums the news forums dont take the replaced variables with it. so on the thread linked above, theres this snippet of code which was used to make a plugin

if($thread['postuserid'] == '1') {
$find = array(
'________'
);

$replace = array(
''
);

$this->post['message'] = str_replace($find, $replace, $this->post['message']);
}

could this code be changed so that i can replace on any thread and instead of replacing _____, could i use it to replace www.oldurl.com with www.newurl.com ?

Is this doable?

--------------- Added [DATE]1389025772[/DATE] at [TIME]1389025772[/TIME] ---------------

so would this work

if($thread['postuserid'] == '1') {
$find = array(
'www.oldurl.com'
);

$replace = array(
'www.newurl.com'
);

$this->post['message'] = str_replace($find, $replace, $this->post['message']);
}

Still unsure how to make it effect all threads