The 3.6 engine can take regular (89 octane)
You can. But you will more than likely notice a performance difference in your power.
The 2004 Cadillac CTS runs on regular unleaded.
The 2005 Cadillac CTS runs on regular unleaded.
The 2008 Cadillac CTS runs on regular unleaded.
The 2006 Cadillac CTS runs on regular unleaded.
The 2010 Cadillac CTS runs on regular unleaded.
The 2003 Cadillac CTS runs on regular unleaded.
The 2009 Cadillac CTS runs on regular unleaded.
The 2013 Cadillac CTS runs on regular unleaded.
The 2007 Cadillac CTS runs on regular unleaded.
The 2011 Cadillac CTS runs on regular unleaded.