Gearbox filler
Older versions of the Comex box seem to have a filler cap which vents as much oil as air. This doesn't do the gearbox bearings much good, or the rear engine mount which goes squashy and falls to bits. In the case of the Aixam, the recommended oil capacity was increased from 700ml to a full litre. Was this to make the dribbling oil last longer? I don't know. I measured a recent gear oil change. The extra 300ml had disappeared in only 3000 miles. The service interval is 6000 miles! Really the oil does much more good inside the casing, and modifying the filler cap is the answer. A later type cap is available I believe the part No. is 3AAC12 instead of 3AC12. It has a pipe connection for tube 3AAC61.
I made my own version using a brass tube into a plastic gearbox cap. A hole was drilled to fit the tubing fairly tight, and after some diligent de-greasing, I secured the tube further with slow setting epoxy. I had some clear tubing, possibly silicon rubber based, and this was connected after the cap fitted into the gearbox. The tubing goes up a foot or so behind the dashboard noise insulation, over the wiring loom or something up there (I haven't seen it for a while!) and dangles back down near the steering rack.
The tube goes upwards to make any oil splash run back into the filler. It goes down again so that dirt doesn't go in the pipe. Note I had 2 fillers, the one with the ladder type baffles on it still let the oil out. See the oily muck on the gearbox top?
Does it work? I drained the oil to change the gearbox bearings 2000 miles later:
This was the volume drained. I'll call that a yes.
Aixam