I have a 2006 chevy colorado and i changed the oil in it the other day. After draining the oil i took the oil cap off to put new oil in it and noticed a white milky color liquid under my cap. I put new oil and filter on and it still has some milky liquid but not as much coolant level is fine. what could be the problem?

 

probably condensation. If you don't have the milky oil in the pan, and its just isolated to the cap, then probably the gaket on the cap isn't sealing properly. Nothing to worry about, you can try a new cap but it may happen again