Back to the basics.....oil.

With winter here and a previous problem with gasoline in the oil, i've had my experiences with thin and thick oil. I was wondering what everyone's opinions were on the effect upon an engine. I assume that thin oil, causes a drop in oil pressure due to reduced resistance, and lack of lubrication when the engine gets hot. My big question is what a heavy oil could do. One might assume that running straight 30w or 40w to break in an engine would provide adequate oil pressure due to it's thickness but I was reading that this could also be it's downfall. From what I read, I gathered that the oil pickup screen can not effectively flow a heavy straight oil because of the surface tension of a heavy oil would make the screen's flow to be reduced. Anybody have an opinion on this? Sorry for the length.:SNSign:

Lets assume that the pump would spin at a constant rate, at idle, 800 rpm. Wouldn't the pump process the same amount of oil (volume) regardless of the oil's thickness(unless my above statement holds true and thin oil would be able to flow a greater volume through the pump compared to thick oil )? I am not a mechanical engineer, so please correct me if i'm making myself out to be an idiot. I think the only variable would be pressure. And yes i'm questioning my own question.