It's interesting to know that one of the specs is that can be mixed. And as you said without harm. My question would be then, if you mix them, could this produce a combination of additives that would not work well together to accomplish what the additives are supposed to accomplish? In other words, it wouldn't be harmful, but could achieve a mix in which the additive combination wouldn't keep the engine clean, or provide the correct viscosity index?
Great response, I would like to know a source to learn a lot more about oil, additives etc.
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in