oil and oil you will be fine bro.. no need to do seperate...... never mix oil and water thats a no no.....
and I am just guessing, but seems you are newer to this, so no need to try 3cc in one injection which was said above {no flame by the way] I know it has been done, but I would not inject that in one spot at once,,, and anyone who knows me here knows i am overcautiuos, but never had absess never really any problem at all... jmo but if you got 3 or more ccs to inject a week rotate em..
tell me what your cycle is, and i will try to help you out bro... but by all means mix em up all good...