I have stock drum brakes on my Electra and I am about to replace the brake fluid. I was thinking DOT4 for its higher boiling point, which should be good for drum brakes that run warmer? The guy at the store sold me DOT3, with the compelling argument that it is more compatible with the seals on classic cars. It happens I didn't change brake fluid today and I will go back to the store tomorrow anyway. So, any second opinion on this?
You are correct. DOT 4 will not harm the seals. The difference is higher boiling point, and nothing more that you need be worried about.
