You may be okay, but I wouldn't risk it because this is a pretty important system. The unfortunate thing is what happens when oil mixes with brake fluid is it contaminates it and permeates it. It is not like oil and water where it doesn't mix.
It would not be that big of a deal if you just flushed your lines but the oil actually swells rubber and causes it to not seal any longer once it is deformed. There is no way to tell when this may happen so even if you flush it, you will be pushing the oil that is still in there through your system and it will infect all your rubber components.
The only real solution is to replace any components with rubber seals. This means your master cylinder, rubber brake lines, possibly the calipers, and maybe even the ABS module because it contains rubber seals.
You may be okay with just some of that like the master cylinder and rubber lines and then flushing the lines with a solvent before you reassemble the system. If you came into my shop, I wouldn't feel comfortable letting you go without doing it all because again, if a seal fails, you will not know until it fails. This is not a system that you want to take chances with not only because it affects your vehicle but you will be on the road with others.
Sorry for the unfortunate news but oil and hydraulic seals just don't like each other.
Thursday, May 30th, 2019 AT 3:56 PM