I've used Valvoline 85W-140 semi-synthetic in a 126 diff. for the past 75,000 miles. I live in a very warm climate - winter is non-existent. This viscosity may not be suited for others.
If the synthetic lube is not right for my MB, I've yet to see why.
1991 300-SEL - Model 126
M103 - SOHC
James Madison - Oppressors can tyrannize only when they achieve a standing army, an enslaved press, and a disarmed populace.
Liberty Firearms Training - After years of trying to regulate California criminals with a never ending stream of gun control laws they have still not given up with the belief that if they make something a crime that criminals will miraculously start obeying the law.