I found a Fitch fuel Catalyst system for my 2008 cts. It attaches to your fuel line and lasts the life of your engine. Supposedly it increases fuel economy, engine oil life and many other things. Runs about $215. I was just curious if anybody has bought this product and how well it really works.
http://www.fitchfuelcatalyst.com/
http://www.fitchfuelcatalyst.com/