I remember GM maintenance using this product in one of my trucks and that engine ran smooth as silk. So, I decided to order Krex and try it out.I have a 2016 GMC with the 3.6 liter direct injection engine, and I use Valvoline Synthetic oil.I added Krex today with engine running and drove it about 15 miles to make sure it had coated the inside of engine well.I didn't notice any change in the sound of the engine, as it already runs very smooth. I did however notice the fuel mileage started getting better. I watched the instant mpg readout and was amazed that it was getting 34 mpg on a straight flat road set on cruise for 65 mph. I went up a slight hill which usually drops the mpg to around 14. The readout held a constant 27!Is that enough to let you know that YES, this product works very well.