By mixing two perfectly good oils you end up with an unknown with unknown properties. Additive packs are carefully designed and now you're messing with that balance.
The whole concept of mixing angers me. It is ignorance and arrogance exemplified. Degreed chemical engineers with years of experience and millions of dollars behind them design an oil for a specific application with the goal of the best protection at the best value.
That a bunch of enthusiasts on an Internet message board think they know more than the guys/girls designing and producing the oils is depressing.
Ignorance all to often runs unchecked... I will not be silent. Don't mix. Pick an oil that suits your application and use it