Originally Posted By: eljefino
There's junk in the bottom of the sump that'd be nice to drain annually.
I agree with eljefino, if you drive less then 12k miles per year, I would definitely drain the entire sump once a year to flush the system.
I personally think the thin oil particles burn off, leaving behind the thicker bits. Over time, it accumulates and you end up with a thicker viscosity. Or worse yet, you end up with a messed up oil chemestry regardless of the top off oil.
If it's that much of a water and you'll gladly junk it once she blows, sure, screw changing the oil. But if it's a good car with a oil burner of an engine, I'd personally try to experiment with different oils / additives to see if you can lessen the burn off and keep the engine spinning for many years to come.