Can i drain all my DOT3 Fluid from the brake system and replaced it with DOT4 to add a littble bit more of resistance to Boiling Point is it safe? my car is designed for DOT3 by the way
DOT3 and DOT 4 fluids are mutually compatible, so no issue using DOT 4 where DOT 3 is specified.
Yes, if you read the label on DOT4 fluid it should say that it can be used for DOT3 applications. Do not use DOT5 fluid in your car.