It sounds like your oil may be a bit too heavy. Synthetic is less viscous at lower temperatures, all else being equal, so it will tend to get moving faster on a cold start. In the winter you should probably not go higher than 10W-40 if you use dino oil and some may argue even that's too high if you park outside. I'm not sure if your 190 has hydraulic lifters but on my 603 engine you can sometimes hear the valve train click when you first start up on a cold day because it takes a couple of seconds for the hydraulic lifters to come up to pressure. No harm done but all the same the faster the oil gets moving the better. Just remember to switch to slightly heavier oil in the summer.

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold