Very well put jmo, you are correct in saying too much excess oil will blow seals but as you say a relatively small amount will cause no harm.
I was once at a friends garage some years ago and a customer towed their car in complaining that it wouldnt start, on investigation it emerged he had changed the oil and filter himself and when he had put fresh oil in he had FILLED it right to the TOP (all 3 gallons of it!). Not supriseingly it wouldnt even turn over!!
