Ok guys I have a 69 cutlass,front disk brakes. I just changed the brake booster and master cylinder. What dot fluid do I use 3 or 5?

 

DOT3 or DOT4 mostly likely, DOT5 is silicone based and not compatible with the old stuff still in the lines.

 

DOT 3 or DOT 4 (higher cleansing agents -- actually much better -- a little bit more expensive)....


Do NOT NOT use DOT 5 -- that is silicone brake fluid -- and NOT NOT
compatible at all -- only for use when the system is fully flushed and
prepared specifically for DOT 5 Brake Fluid....

 

Thanks guys . i thought it was dot 3 ,but when you start reading you get so many different answers, so I came to the wright place thanks again.

 

the synthetic stuff i just bought was DOT 3&4 compatible !!!! FYI