Sorry for the late response but I was looking around and came across your thread. I have been using the Rev-X for about a month and a half and I definitely notice a big difference when I first start my truck in the morning. It's much smoother and doesn't have that rough idle except for just a few seconds. However, the weather hasn't gotten cold yet so I guess the real test will be this winter. It's expensive, about $70 per treatment. For what its worth at this point I will add it again at my next oil change. There are some videos on YouTube with people doing before and after cold starts, check em out.

Good Luck.