'40's brake fluid

I need to add brake fluid to my '47 International pick up. the manual calls for Wagner lockheed brake fluid no. 21 containing no-mineral oil.
Question is;
- Is there a universal brake fluid that will work?
- What will happen if I use the wrong fluid?

 

I have never looked in a manual to see what kind of brake fluid to buy. I just always use what they have at the autoparts store. look on the shelf you will probably see some that specify disc brakes and some that doesn't. Either will probably work but I would get the one that doesn't specify disc brakes if I was worried about it.

 

dot 3 and dot 4 fluid does not list mineral oil as an ingredient.

 

What they are telling you is that you need to use brake fluid like a DOT 3 or better. Back in the day some people would use hydraulic oil because they equated hydraulic brakes with hydraulic jacks or anything else hydraulic. If you put hydraulic oil in the brake system you ended up with softened rubber parts, blown out master cylinders and wheel cylinders and junk brake hoses and a big bill and big project. And yes, it still happens today. So, just use a good fresh can of Brake fluid. If there are others that are a little more familiar with the synthetics, lets hear about it.

 

As suggested, just use "regular"brake fluid, Dot 3 or Dot 4.

If you are temped to use Dot 5 or some other "premium" product, realize that some of those magic brake fluids are not compatible with some seal materials. And that while DOT 5 does offer some potential plusses, it isn't better in every way than "regular" brake fluid.

 

I have seen that done a number of times on hydraulic clutches. Even when there are two identical reservoirs side by side, someone thought the brakes need brake fluid and the the hydraulic clutch needs hydraulic fluid.

 

I actually used Cheap Scotch once in Baja, but it got us to Hermosilla.

 

Used Dot 3 with no problems. thanks everyone, also I keep a bottle of scotch just incase I have problems with my brakes or get thirsty