May not be applicable, but my inverted 930 does the same thing (assuming it pushes oil out the vent when the car is driven). I tried various things that reduced the oil pushed out (my vent is located just forward of the fulcrum plate, on the main case). Eventually I had to go with a catch can. I guessing that if I relocate the vent, the problem would go away because this is not due to expansion or blow out (still does it after reaching max temp). It appears the my vent is located where oil is slung up from the gears, so perhaps moving it to a less active portion of the case would help.