I wouldn't waist my time with the ltr oil separator. The above post had 2+ QTS of oil in his crankcase and that is why he is having trouble.
After it gets warmed up do you shut it off then drop dipstick in and check or do you leave it running?Actually it's drains back from the oil seperator under your left rear fender.
Very little chance of debris being carried back to your engine. If you over filled your engine oil you will get oil in your airbox.
Warm up your engine so the oil expands then uncrew the dipstick wipe it off and drop it back into the engine case. DO NOT screw it back in. Then pull out and take your reading.