Loosening the cap whilst running will be very messy as the oil is under a slight bit of pressure and will come out the seal at the lowest open point, in theory leaving any air at the top.. The little nut should only be torqued down to a very low pressure and should come off easliy, if it's turned in the correct direction.

I know it's not correct but I don't bother bleeding the air out as I use a centre stand . As an experiment once, I checked the bleed nut after waiting for the fan to kick in and there was no air.

Since then and many filter changes I don't bother with it.

__________________
I have a lot of growing up to do. I realized that the other day inside my fort.