My 2010 G5 Deluxe is completely oil tight even using slippery Mobil 1. This was not always the case, I had several leaks when I got it, Sump, Oil Filter Cover, Oil fouled Air Cleaner & Airbox.
SOLUTION: Silicone sealant on Sump threads & behind oil filter cover. I rerouted the crankcase breather hose via a longer hose, over & to the end of the rear fender (any over filled oil can escape this way) Just like the 1960's Brit bikes did. Recently when we moved, I needed to park the G5 in our entrance hall & living room - not a drop on the white tile floor. My wife even got to bond with it, Ha!