First of all; never mix any brake fluids until the manual or brake fluid code tells you so!!!

From the shimano website; "The use on systems with DOT fluid may damage the rubber plate.

Note: Never mix different brake fluids. Use only genuine Shimano mineral oil. If other types of oil are used, it may cause problems with brake operation and cause the system to be unusable"


DOT based oils are mixable IF they are FULL synthetic, with modern oils you can mix DOT 4 with Dot 5.1

You can recognize DOT fluid because its aggressive to paint and it bites on your skin.

Most mineral oils are not mixable; since you mixed two kinds, you probably need to bleed again.
Contact your LBS and explain the situation