All the oil change procedures I've seen recommend changing oil on a warm engine. Aside from the lower viscosity of warm oil, is there any advantage over draining oil after the engine has not been run long enough that most of the oil has drained into the sump? It would seem to me that all the stuff that doesn't stay in suspension (carbon particles, water, etc.) would migrate to the bottom of the sump given enough time and would be first to come out when the oil is drained. The drain is always at the lowest point of the sump. Obviously what's in the filter will (mostly) stay in there. But, is there an advantage to having the rest sprayed all over the engine internals by running the engine before draining the oil?