Index: feed.php
===================================================================
--- feed.php	(revision 11451)
+++ feed.php	(working copy)
@@ -543,14 +543,14 @@
  * @param string $url URL to retrieve feed
  * @return WP_Error|SimplePie WP_Error object on failure or SimplePie object on success
  */
-function fetch_feed($url) {
+function fetch_feed($url, $lifetime=43200) {
 	require_once (ABSPATH . WPINC . '/class-feed.php');
 
 	$feed = new SimplePie();
 	$feed->set_feed_url($url);
 	$feed->set_cache_class('WP_Feed_Cache');
 	$feed->set_file_class('WP_SimplePie_File');
-	$feed->set_cache_duration(43200);
+	$feed->set_cache_duration($lifetime);
 	$feed->init();
 	$feed->handle_content_type();