2016 Kia Sorento SX V6, 2014 Kia Cadenza Premium
Small point here but what can collect on the back side of the valve is not carbon. Carbon is a by product of combustion. What is collecting on the back side of the valve comes from oily deposits generated by a crankcase breather. In a non-GDI engine these deposits would be washed off by the air/fuel mixture passing the valves. It would be easier to clean them before it gets too bad from many miles of in-attention.Thanks for the info, Steve. I guess what I'm getting at is if a solution like this spray is sufficient or if there are more steps recommended to removing the carbon buildup?