A quality oil with high detergents will become dirty quicker than a cheaper made oil. When oil is working properly, it will clean as well as lubricate. If your oil stays clear and clean, either your transmission/engine is extremely clean or the oil is not doing its job. Someone mentioned Amsoil earlier, I am an Amsoil dealer and would not run anything other than Amsoil.
Your dealer may have used a high quality oil and it is working properly. Hopefully, that is all it is and not a radiator issue as mentioned earlier.
