I started used Mobil 1 5W-30 a few weeks ago in my 2000 Ford Crown Vic - and it runs fantastic in the cold. In the morning when its around 40F, the car would just tear a$$ as if I had warmed it up for 15 minutes. With dino juice, even with API SL Pennzoil PureBase 5W-30, the engine would seriously lug for the first 2 miles - the oil wasn't flowing fast enough or something. With Mobil 1, the engine revs a LOT smoother in the cold. I wanted to get good oil for this engine because its supposed to be OHC, and OHC is usually picky w/ its rings and valve stem seals/oil passages due to tighter tolerances. My other engines are pushrod OHV engines (Ford 300 I6 and Ford 302 V8) which can pretty much take a beating and not squirm. I'm such a synthaholic that I went to synthetic Pennzoil 75W-90 gear lube and Mobil 1 ATF for the power steering as well I'll continue to use Mercon-V for my 4R70W though ... it seems to keep the tranny shifting properly. Mobil 1 ATF and other non-Mercon V ATFs and the 4R70W don't quite mix right.