When it comes to motorcycle maintenance, you can be "old-school", meaning that you stick to your conservative approach. That's not how I view things: I'm from the new school, advocating evolution and looking to understand novel concepts and ideas.
These two schools of thought clash on a lot of subjects. Let's take engine oil change for example. When's the better time to do it? At the end of the season, when you're about to put your bike away in the garage or a warehouse, or at the start of next season? Conservative mechanics will tell you it's wiser to perform an oil change come springtime. Personally, I believe the exact opposite. What do they base their decision on? I have yet to hear a solid reason.
I believe that oil change should be performed prior to storing your motorcycle. My reasoning is based on facts that were demonstrated by petrochemists as well as findings of maintenance specialists on damages that occurred during the warehousing period.
Oil that was put into contact with the air inside the engine, not to mention the heat and various contaminants, is more prone to deteriorate, even if it contains anticorrosion or antifriction additives. It loses some of its initial properties in the first three months of use, especially with a high mileage (5,000+ km). To be more accurate, I would say that oil ages at a normal pace and winds up losing its lubricating and protection qualities. As a result, it can no longer stick to the inner surface of the engine for long periods of time, let alone protect the steel parts inside the engine.
Let's say you've travelled a little more than 3,000 kilometers and had your oil changed barely a month ago. Is it really necessary to change it again before you store your bike in the garage for the cold season? The answer is yes! Why? Because it won't properly stick to the internal parts throughout the winter months, coming off the surface and allowing it to become impregnated with moisture.
Bottom line: you need to replace not only the engine oil but also the filter. Don't forget about the filter: it contains part of the used oil and could therefore contaminate your new one.
First, the replacement oil will become oxidized and corrosion will adhere faster to the metallic parts inside the engine. The first parts to be affected are the piston rings as well as the intake/exhaust valves. If they corrode, the impacts are significant. A jam between the cylinder liner and piston rings can end up locking and scratching the cylinders. The rings could even break or become irreparably damaged. That's not all: the valves will lose airtightness, which will reduce performance and make engine starts harder.