why are Californians still warming up their cars? I thought that was no longer necessary.

[1-Old-Man]

6. There are some very good reasons to let an engine warm

There are lots and lots of parts that are made of different sorts of metals and plastics in that engine that change size a very little bit as the temperature of the engine comes up to its operating temperature and they expand at different rates. So when you first start up the engine they don't fit together exactly as they will after it warms. By not putting the pressures of use on the engine during that warming period you decrease wear on the parts. So that's one thing. The other is that it takes just a little bit for oil to get flowing through all the little nooks and crannies (galleries, passageways, and small orifices actually) so they can be properly lubricated, cooled, and for some parts sealed as well. All in all its still a good idea to give it at least a little bit of a warm-up before you head on out; thirty seconds, a minute, it all helps.