I used it when I first purchased my SRT6. I know this will be controversial, but I have used it on a few cars and have never had a problem. The first step is to do an engine flush, and then you add the CERA TEC Engine Oil Additive. After that, with every oil change, you use step 2:6 Cylinder Additive Kit (Step 2) - Liqui Moly. This includes an oil additive and a fuel system cleaner.

I found the SRT ran better and cleaner.

As I have stated, I used this on my 2013 S4, 2011 C300, Mazda Speed 6, and my new to me Cadillac CTS4.