Dilantin administration

Help! I've been taught that Dilantin was only to be administered with Normal Saline. I've seen cloudy tubing with it was mixed with concurrent fluids of D5LR, D5NS etc. In fact I believe drug precipate from mixing these drugs caused port occlusion a few years ago. To prove my point, I tried injecting Dilantin in a line primed with D5W and guess what..nothing happened. Have I been misled? The books say precipate may occur. Taking a chance on losing a port is not worth it in my opinion.