Just inspecting, looking at things, anticipating problems etc. I noticed that the top fluid tank shows just a little over half full as I look at the see through area from the drivers side of the truck. What is actually the recommended fluid level in the tank? I presume not totally full. I was looking at it with the top up but just unlatched so don't know if in that position some had been sucked up or that level is what is should be. I presume overfilling is not good nor running low either. What say you?