Dear Tim;
It's because these (remote) filters present far more of a fire/explosion hazard, than the "cleaner oil" benefits could ever provide.
One simply changes @ 3000 using commercial oil.
The pin is the same diameter throughout an surounded with a copper bushing, where 'relocation' is not a problem. Sometimes there is some temporary seepage. Some just remove totaly "tap" and install a threaded plug, on the (2nd design).
The "by-pass" line provides equal distribution of oil W/O the filter unit, on the (3rd design).
Ron is using it (#2 model) to avoid moving his pin etc.
Happy trails.
