As it's summer, I have Mobil-1 15W50 in my 400E now, no problem at all, in Canadian winter, I run Mobil-1 10W30/5W30.
I get much higher oil pressure with 15W50 than with 10W30, 1.5 bar vs 0.3 bar.
99 BMW 540i 6-speed 110K Km
03 SAAB 9-5 wagon 80K Km
92 400E (Sold) 245K km
Still missing the days with the Benz, it kept me busy.