My own "unscientific" observation and comparison of some oils at about -13. Went into my unheated garage last night in Lincoln NE temp of -13. The 5w20 conventional Traveler oil that I use in both of our Hyundai poured very easily which I would expect with a 5w winter type oil The Traveler 5w30 that goes in our Forester also poured equally well which I expected since the 5W( winter) designation. I also had 2 qts of Honda dual pump fluid and it was sloshing around quite easily.I had a bottle of subaru power steering fluid and it would pour easily. Also had a bottle of Prestone Asian power steering fluid that I had from before I traded out our CRV and it was thicker than molasses and would have barely poured out had I tried. Also had 2 qts of shaaffer 75w90 ( for our forester rear diff which was thick but certainly not frozen solid. I was a bit surprised that the Prestone Asian PS fluid was so thick. Used it for years in our Honda in very cold temps with no power steering issues, but its thickness at that temp compared to Subaru PS fluid was a stark contrast. Also had a qt of Briggs & stratten SAE30 that I keep around for my mower and power washer. I expected it to be like molasses but it flowed almost as easily as the 5w oils. It flowed very easily at that temp. I did not have any other SAE 30 oils to compare it to, so my guess is that since Briggs SAE 30 is an oil used not only in lawn mowers, but also in snow blowers, that Briggs SAE 30 oil must be able to pour in low temps since snowblowers must start and operate in very low below zero temps. I would have expected a straight 30W to be a bit thick at a -13 temp, but to my surprise it was not.