How bad is this? Moisture in oil.

[HoosierJeeper]

I run Mobil 1 full synthetic, and I run either 10W-40 or 15W-50. The reason I run the higher weight is to protect the engine better and I also do not care if it hurts my MPG.

I don't think that's doing it any favors in the cold....or in general. Something to ask on BITOG.

 

[GunnerSchenck]

It's not. It's making his engine work harder for no reason whatsoever.
People do it because it "quiets down their valvetrain"... why? Because it's keeping your valvetrain from moving as freely as it should, not protecting it.