I've been making my own blend lately. Ige changes the oil on her FZJ80 pretty often, I keep her old (synthetic) oil in gallon jugs. When my Rotella dino gets low, I top it off with the used synthetic...
I keep the jugs full, the bad stuff sinks to the bottom over time, I use the stuff off the top.
I keep the jugs full, the bad stuff sinks to the bottom over time, I use the stuff off the top.