I am converting my front drum to disk and was getting ready to bench bleed the master cylinder and put fluid in. It been some time since I have bought brake fluid for any of my cars. Question is about the synthetic brake fluid. Is it better to use it or the regular DOT 3. Is it compatible with the left over fluid in the lines ?

Dot 5 silicone based synthetic is NOT compatible with Dot 3! It tends to want to leak!

Do some research on this ite and learn about your options.............

I used DOT4 synthetic.
I beleive it is compatible with DOT3 (my entire system was new...)
DOT4 is not a silicone fluid.

For the money valvoline dot4 synthetic is good, and it's compatible with dot-3 fluids too.

If you want something with a higher boiling point ATE Super, Motul, or Castrol SRF are some of the best fluids.

Thank you for the info.