Jim,

The MB dealers have 0W40 Mobil One in their fancy shopwide oil dispensing system. That is why they recommend it. This covers a pretty good temp range and is probably okay.

That said, oil weight is pretty fundamental in these engines. Many very new engines with roller lifters and some other considerations require lighter oils, but for the 104 I would go by the generic chart, a copy of which is linked in the post previous to this one. It indicates 15W40 which would be a dino oil and 15W50 which would be a synthetic.

In our climate for your engine I just don't think you could go wrong with those weights. Once Winter gets here it wouldn't hurt to lighten up a notch to maybe 10W30 or whatever is the next lighter weight in the alldata chart.

I wouldn't get too wrapped around the axle over this. Pick your favorite brand premium oil in a reasonable weight for the season, keep it changed and it will probably run forever given the way you maintain your cars.

Have a great day,