The Shimano systems are designed to be used with mineral oil. If you are questioning which one was put in you system and now you have mixed them i would suggest draining the system and putting the mineral oil in.

"After you fix or replace the damaged line, you'll need to bleed your brakes, which brings up the subject of hydraulic fluid. In general, disc brakes use one of two varieties of hydraulic fluid: mineral oil or DOT fluid. Unfortunately, there are different concoctions of each, and you shouldn't mix the different kinds-ever. Don't mix Shimano's mineral oil and Magura's mineral oil. Even more disastrous is mixing or replacing DOT fluid with mineral oil, or vice versa. Doing so will probably eat all the rubber seals in your brakes and cause costly damage and a severe case of no brakes. The only quasi-exception is that you can replace one DOT variety with another-for instance, you might be able to replace DOT 4 with DOT 3 (the larger the number, the higher the boiling point of the fluid). However, you must flush out all the fluid you're replacing, which is time-consuming. In the end, you're simply better off just sticking with the fluid that comes with your brakes. "