Thinking your oil is in the same place as mine, 09 FLHR. the oil tank is vented with the tranny vent hose on top of the tranny..
I have never tied to Feel If there is a suction there .. I assume you have the bike running..
How are you placing ?
Hand ? over the oil fill hole?
I Could Imagine a little but not a lot.. I'll have to Wait and read what you answer here to make it More Clear to me and I'll try mine to see..:naughty