Well to cut it with the oil you can either pull 1cc for 1cc or 1cc for .5cc If not filling the pin all the way pull plunger back all the way and use the extra room to shake / mix the oil. Otherwise if you know how much oil is left in your vial since you keep track of your shots then mix in the amount you have pulled and then use simple mathematics to equate mg per ml. EI pulled 5ml out of a 10ml bottle replace 5ml of GSO then pull two ml to get what is now in a ml dose. If 15ml of 200mg left and 5 used then add 5 then 15ml x200mg = 3000mg add 5ml GSO oil then 3000mg / 20ml solution = 150mg per ml or in a 10ml bottle say you have used 3 ml, so 7ml x 200 = 1400ml add 3ml GSO oil is 1400/10 = 140mg per ml with new mix.
Remember when you go to add the GSO to a vial you need to suck out the same amount of air before trying to add it. IE suck out 3 ml air then add 3 ml GSO. Depending on how much Benzoil Alchohol is in it you may only need to dilute slightly or 2/1 I would start with a lower amount then increase if needed.
Like I said you can mix them in the pin if you are not using the whole 3ml just pull back far enough to have air in it so you can shake it a bit to get them to mix.
