I know that my ears will be burning when people read this, but I have used Amsoil all my car driving adult years. Currently in my 97 C280 I'm using the Amsoil 15w-40 Heavy Duty Diesel and Marine Oil and use it in Moms 91 Audi. I am the second owner of the C280 and I can't believe the MB Dealer actually used Kendall 10w-30 in the motor.
If you look at the specs for the Amsoil 15w-40 vs. a Kendall, Valvoline, Pennzoil, etc, etc, it beats all of them on each and every spec. I live in MN and concerned with pour points during the winter months. In the summer months, I'm concerning the High Temp Shear and the 15w-40 is fabulous.
It's my opinion that everyone should be using at least a x-40 weight oil in their motors. Whether it be a 0w-40 for the newest motors to a 10 or 15-40 for the 80s to 90s motors.
No, I am not an Amsoil dealer, but believe in putting a superior lubricant into a superior engine (eventhough the 104 in my view is not a superior motor)
Hope this helps!