I switched from 5 to dot-4. Flushed a gallon of dot 4 through it. The dot 5 rises to the top so it was easy to get all the old stuff out. It's been 2 years and had zero issues, planning to flush again soon as per the 2-year maintenance recommendation. One downside of dot-5 in vehicles is the fluid does not absorb moisture, so it puddles near the bottom of pistons and causes putting and rust. It does last longer with poor service, but not good for vehicles that sit for extended periods. 😕 just my opinion.
I'm assuming you must have used flushed-out DOT5 because all DOT5 is purple when new. The general consensus is that if you mix it with DOT3 in a master cylinder weird chemical reactions occur. These reactions cause rubber seals to fail and the cap gasket to expand to 3 times its normal size. Or it turns into jelly. Or nothing seems to happen. I don't see any chemical reactions occurring in the jar. What would happen if you threw a piece of rubber in the jar and let it sit for a few days?
