-21F this morning, fired the Navigator up (filled with Schaeffer's 5w20) after sitting outside all night. Turned over freely and started right up, only noise was from the power steering pump, which still has the OEM fluid. For a synthetic blend, I am very impressed with the cold starting performance of the Schaeffer's oil.
Started the Grand Marquis (Pennzoil 5w30) shortly after, it started fine, but turned over much harder than the Navigator. Both vehicals have the same battery of similar age so I am blaming the difference on the engine oil. If not for an annoying oil leak, I would drop the conventional out today and refill with synthetic. On the bright side, the power steering (filled with AMSOIL synthetic ATF) was silent.