What's best, checking oil hot or cold?

[rickjordan]

The reason I ask this is because I have always believed that checking the oil when it was cold would give a more accurate reading. However, the owner's manual tells you to check it when it's at operating temp. I would think waiting until first thing in the morning would definetly give all the oil a chance to make it's way down to the oil pan. Is there that big of a difference in the oil level when it gets hot. I know that it thins out, but does it make a noticeable difference on the dipstick?