2000 GMC Sierra 1500 4x4 w/ 190K; solid truck; no oil burn; no leaks; always been on Mobil 1 full synthetic. My last two oil change intervals, the oil seems "muddy"; not milky....but a dark milk chocolate appearance.....?? There is a small amount of condensation on the oil cap when I remove it; local oil change provider says that's normal. Geesh. No overheating or oil in water like a cracked head. It has always "used" a little coolant (pint or so) every 3-5K.

Thoughts?

Bryant