Ok, hope I don't get flamed out of this forum for this one. The 4200xl comes with a needle type vent for the hydro tank. Most of you have probably seen it. The question is should the vent be open or closed during operation? Is this a one way needle valve for pressure to escape if need be? I know you can add oil through the pressure fitting(blue.) I've been running mine pretty open as that's how it came. I've been coming across vids and threads of people closing it during operation and just opening it when adding oil. Any thoughts? Here's the vent valve. For the most part just wondering if I'm missing some performance with it open during operation.
http://store.rc4wd.com/Ventilation-S...nk_p_1823.html