Lineslinger,
I use to have a Mike's XS reed valve up in the battery compartment but I soon discovered that the oil in the tank would get milky and when drained when doing an oil change, there would be water at the bottom on the oil tank. That reed valve needs to be physically attached to the engine to keep the condensation at bay.
I went to the Comstock design at the back of the 850 engine and never had issues since. the heat from the engine helps cook off any condensate. Where you mounted it up near the oil tank makes it act like a water trap for condensation, IMHO.
I don't drain the wet sump plug either with the Comstock design, as it quickly discharges any excess oil in the sump rapidly back into the oil tank. About 30 seconds is all it takes and then all I see after that is the steady percolator pattern of oil return from the rear tube from the oil pump return line. YMMV
Cheers,
Tom
