I have a half pint of Dot 4 thats gone unused for a long time and I'd like to use it up and get rid of it. My question- I'd like to remove an equal amount of the stock Dot 3 and use up the Dot 4. Can these two fluids be safely mixed?

 

You probably could BUT an opened can of brake fluid that has been sitting around for a long time probably has absorbed enough moisture from the air to make it worthless.


Just get a new bottle of fresh fluid and don't try to save $5 on what stops your car.

 

Thanks for the reply. The bottle is unopened so what do you think?
If it is still questionable, I'll just give the bottle away.

 

Unopened does make a difference.
How long is a long time?
How was it stored?
Plastic bottle?


Just play it safe and get fresh fluid.
If you have some left after doing the brakes flush the clutch system.

You can mix DOT 3, 4 and 5.1 without problems.