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Originally Posted by Seabass
I'd love to know why an oil change doesn't do it!.....
What advantage is offered by lighter oil? Higher operating temperature?
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A lighter oil (the first number in the viscosity) will flow better at very low ambient temperatures. There is no difference at operating temperature, that is related to the second number in the oil viscosity. That's it. It has no connection with the condensate you are seeing in your oil, that isn't coming from the oil. The condensate (it is not called sludge, which is very different, and it is not cheese either) is from moisture in the air, that condenses inside the engine. When you start it up cold, that moisture combines with the oil. Every start/stop and hot/cold cycle produces more condensation. Normally, if the engine gets good and hot, the moisture boils off after a while, on each trip. Then, you have no problems. If you have lots of short trips, with no long trips mixed in, the condensate doesn't boil off, and builds up over time. Enough of it produces an emulsion of oil and water that has a pasty consistency, but all it is is oil and water mixed. Because it contains water, it can freeze. Because it is semi-solid, it doesn't flow and therefore it clogs up the separator. More frequent oil changes help. Some specific oil blends may have better performance at holding it in suspension, but that is because of the different oil, not the different weight of the oil. Oil doesn't affect operating temperature, that is regulated by the engine.
Best bet is a series of hot oil changes (not too close together), followed by driving it sufficiently long to get it good and hot every now and then, if you can't do it on every trip. A heated garage probably wouldn't hurt, but short of that there isn't a lot you can do. Some people have suggested block heaters, but they don't address this issue and you would have to heat the entire block continuously, not just immediately prior to startup. That would get expensive.