| To try and locate a leak, dust the joints down lightly with talc, apply a little pressure to the lever (tie wrap or similar) then leave overnight.
If there's a slight leak the fluid will the forced out and caught by the talc, this makes it a lot easier to see as it'll appear as a clumped mass (you can do the same for oil leaks)
Also, check the reservoir and hose, if it's kinked or blocked it'll give the impression that you're losing the lever because the M/cyl can't be refilled to compensate for the pad wear ( had this at Cadwell, it's disturbing!)
If it's not leaking and the lever's fine, swap fluid type to 5.1, it should be a lot harder to boil the fluid then, and if I remember rightly it's less hydroscopic than 4. | 
Hybrid Mode
