I am looking to do a brake fluid flush on my truck in the near future. I was at O'Reilly's tonight, and all they had was their house brand and Prestone Synthetic DOT 3. They had another brand of DOT 4 I didn't recognize. Are there any recommended DOT 3 brake fluid brands, or is any fluid certified to fit requirements good to go? Also, how much do I need to do a fluid flush? In the house brand I could get up to a gallon.