I have 2 cans of dot 4 that I brought for my car about 2 maybe 3 years ago,which I misplaced so I brought 2 more, I want to change my brake fluid in my car and was wondering if I could use it or if I should throw it out. Thanks

 

Shelf life is indefinite if the seal has not been broken. Once you break the seal it's the moisture in the air that attacks the chemicals and shortens shelf life. What you have is safe to use.

 

They say the struff to get is the silicone-based brake fluid, as it will not absorb water like the glycol-based older stuff does. Saw that on Dream Car Garage today

 

If you plan on using silicone fluid, you must flush your entire brake system first. With the exception of silicone brake fluid, all other brake fluids are polyglycol based. If you mix the two fluids you change the viscosity and it will change the way some high performance ABS systems operate (not to the degree of poor braking but it does make some changes depending on the ABS system). Silicone and polyglycol do not mix well. Silicone is a excellent brake fluid but even then you can trap moisture in your brake system. Since water (moisture) is lighter then silicone it will travel to the bottom of the fluid reservoir, from there the moisture will work it's way down to the calipers and form tiny air pockets with moisture trapped in them. If your vehicle sits for extended periods of time, corrosion then forms, etc,etc,etc....
If you go on the web there is much to read about pros and cons of silicone based brake fluids.......They are good and it's a personal choice on what you use but do not mix the two.....