Nice, this one is helpful. Also, another example of blackstone picking up an additive in the report when not being told about it like they did with me when I tried an additive that was silicone based, blackstone is great imo. So yes you can mix oils, but what is the gain? I often wonder if tossing a quart of redline in a 7 quart sump would it give benefit over just 7 quarts of one random oil. Something to consider if someone gets some hemi tick and doesnt want to change the oil for some reason, maybe just add some redline like this guy did. Different oil as an additive? Or weight for that matter, use a thicker oil as an oil thickner but less then a stabilzer or using the heavier weight by itself. Interesting, some paper on machinelube puts the "best" oil viscosity at somewhere around 35, but I have yet to see any 5w35 oil on the market. Best meaning balance of protection and flow, this paper was pre fuel mileage hysteria. Generally I don't prefer mixing, but as long as you are considering a strategy who is anyone to judge that?