what type fluid for 57 rocket 88 power brakes

 

Dot 3

 

Type 3 or 4 will work. They can be interchanged.
Just don’t mix Type 5 (silicone based) with 3 or 4.
If the car is new to you and you don’t know what is in the reservoir then suck a little out and see if it blends with what you want to put in. Type 5 will turn milky if you mix it with 3 or 4.
I had a Buick that had type 5 in it and didn’t know......had to replace every component of the hydraulics!!

Bill

 

Motorcraft DOT 3 has good specs...if my research is correct, it exceeds some DOT 4 formulas. IIRC the trade off is 4 absorbs moisture quicker which could matter on an infrequently driven car.

Now for the big question...would that be "Keeping your GM car all GM" ???

 

The 1957 Oldsmobile Shop Manual specifies GM brake fluid No. 11.

 

Thanks sir