Just my opinion and what ive come to understand (or misunderstand so check for yourself) about DOT 3-4 and DOT 5 brake fluids.
Dot 3-4 is water based, Dot 5 is silicone based. Don't mix them, flush thoroughly before converting from one to the other.
On the other hand, maybe post the short term and long term findings of not flushing and mixing of the 2 types of fluids in your project, I know I for one would be very interested in the outcomes.
H2O always, always finds its way into the brake system PERIOD.
Dot 4 easily dissipates the sneaky H2o throughout the brake system and dilutes it making it a non-issue.
Dot 5 on the other hand, does NOT mix with water and has a habit of accumulating in low points/bottoms of the brake lines and system.
As Dot 4 collects moisture, it becomes increasingly corrosive throughout the system attacking mostly the master, proportioning valve, wheel cylinders and calipers.
This is why most highly recommend servicing the brake fluids.
Dot 5 allows tiny water drops to sit in a relatively small areas and do the wonders that water does to metals so efficiently and effectively.
We affectionately refer to as rust and rust is no friend to anything about this hobby! So the water just sits and works like a microscopic drill bit until it breaches the barriers we call brake lines. Scary part is it could cause a complete hydraulic system failure (leak) possibly without warning and most likely at a emergency stopping situation.
Maintenance is a must with all aspects of this hobby folks.
These are my expressed opinions and are not the opinion of the station or this broadcasting service.
Copper