Passon Performance 4spd conversion with hydraulic clutch- Any guess about which hydraulic fluid?

MRGTX said

As we all know, DOT3 and DOT4 are not compatible and it could be either one in the system.

Click to expand...

Not true. As stated, they are 3 and 4 compatible and can be mixed.
It would make most sense to use the same fluid as you are using in your braking system.