First, re 1984GL's comments about checking the thermostat, something that I always recommend is to rip out (literally take a hack saw and cut out) that whole flapper mechanism -- just unbolt the airbox (one bolt releases it from the bulkhead beside the radiator) and start sawing. The problem is that you never know when it's going to fail, so checking it when you change the air filter isn't adequate -- too infrequent -- and when it does fail, it will cook (i.e., destroy) your very expensive AMM ($300+). So after removing that entire "flapper" mechanism, I like to cut a little circle out of sheet aluminum (roof "flashing"), glue it (marine 3M5200 is very good) over the hole to the heater hose, and then -- if you want -- spray paint it black. This keeps the appearance (for emissions examiners) of remaining intact, even if they peek inside (which they won't), but it also ensures that the only air coming into the air box is from in front of the radiator rather than behind, which is the coolest source of air. I've started up my cars (thus modified) in countless icy mornings in New England ski country, and have never had any drivability ("icing") problems.

And about Art's comments about Quickie-Lube places, just DON'T!!! I'm also on a few Mercedes owners lists, and I can't tell you how many times folks have sadly reported real disasters from having used them. Examples include:
(1) the boys (I won't dare call the techs) stripped the threads from the drain plug and it dropped out, along with the crankcase of oil, somewhere down the road;
(2) or they took it upon themselves to replace the screw-in original drain plug with a rubber plug (ostensibly to make future oil changes faster), which also falls off down the road
(3) they forgot to do any number of other critical steps, leaving the car to be damaged as it's driven down the road.
They're all about *speed*, and that's apt to result in mistakes. Don't ever consider using them for anything!