If you pull the fuel line off to let it run out of fuel in the fall-that's a problem. The VRO fuel pump will keep running and will keep sucking oil thru the oil line. As the engine slowly runs out of fuel, it will continue to pump oil into the carb bowls. When the engine finally dies, the carb bowls will be filled with oil. When you go to start it up next spring, you will have a heck of a time trying to start it with all that oil- which will need to dissipate. You may have to remove the carb drain screws, to drain the oil out. While out, prime the fuel hose to get new fuel into the carbs. After priming for some time, the new fuel will start to mix with the oil and flow out the drains. Then re-install the bowl drains. It's a lot of work, as you have found out.