It might be... It's highly not recommended to mix regular and synthetic oils.
No, you can even mix synthetic with conventional oil. It will do no harm at all.
Yes, you can. It is even sold as a Synthetic Blend.
Yes, semi synthetic is a blend of synthetic and conventional oil already.
Yes.
Yes
Yes, you can even mix them.
Yes, you can even mix them.
Yes, they even sell it that way.
Yes, you can even mix them.
That's okay.
not really
use it, it is ok to mix