I have had mine on over 100,000 miles now. It may not be cost effective but I would not be without it. Where I live,Nevada's high desert,it is never needed in the winter unless I am climbing some long hill. Nice and quiet without it engaged. In the summer when I am stuck in Las Vegas traffic and the ambient temperature is 105*+,I run it all the time. That way my temperature never goes above 190*. I had Carson City Dodge install it and it has been a worthwhile addition.