Is it okay to mix dot 3 OEM brake fuild with dot 4 ones? A shop just did a brake bleed for my car, but they refilled with dot 4 Endless brake fuild. They didn't flush the system. The mechanic said no problem, but apparently I found out that it will get a even lower boiling point than just used regular dot 3 fluid. What should I do now? Any help is appreicated, thanks.

 

Your perfectly fine, a normal full bleed actually flushes the system. It may be lowered up to 5 degrees , but considering you had Dot 3 in it before, your not racing the car at a national level where it will matter.