My opinion on this is if you are close to an oil change change it before you put the car away and when you take it out of storage just drive it the add pack in the oil will be in fine shape for a full run in spring.
My expieriance working on small mower motors has shown that if you leave dirty oil in a motor for an extended period of time if you pull the dipstick the oil will look clean?? Why? The reason is the sludge or impurities separates from the oil and sits in the bottom of the oil pan I have seen this many times. But if you change out the oil then put fresh oil in get the motor good and hot then put it away there will be no sludge that will build in the oil pan.
This is the practice I used on a Briggs & Stratton powered 1979 Wheel Horse tractor and last year when I rebuilt the motor the oil pan was spotless.