Sounds good. Since you have a guage, I'm now comfortable that the light is indeed the low level light. There are some later cars, such as the new E-class that do not have a guage, don't get me started on how much I disagree with M-B on this.
I also use 15W40, my favortie brand. I change my own and I change it hot. When you go to Jiffy Lube, see that the engine is at operating temperature. There are more contaminants suspended in the oil that way, rather than clinging to the sides of the engine and internal parts. That's the main reason you change oil often anyway, it's the only way to clean the inside of the engine.
'84 Euro 240D, 516K miles
'88 300E 5 Speed
Over 800,000 miles in