Does home heating oil settle, fractionate, or deteriorate if it sits in the tanks for years?

I live in the Northeast and mostly heat my home with free wood from my property. The house is equipped with a ~10 year old oil fired, hot water baseboard system. I have two 275 gallon, (1000 liter), oil storage tanks in the basement that stays at a relatively constant 56F, 13–15C all year.
I only turn on one tank at a time and my furnace only runs when I am lazy (cold mornings) or traveling.
Since I use wood, the oil in my tanks can, and often does, sit for years. On average, I might go through one tank per year. When one tank gets near empty, I switch over to the other tank and order a load when the price is low, usually in the summer.
A “normal” house only has one tank, burns 1000 gallons, 3800 liters, and gets oil delivered about 10 times per heating season. The oil is always “fresh”. Obviously, my usage is not normal.

Is there any disadvantage to running this way? Is the oil breaking down? Is there data that shows how/if oil changes over time? I have “googled it” already and only see information from sources that want to sell magic elixirs that are “guaranteed to take inches off my wast, make me hard, and increase my bra size.” I can’t find a reputable source that answers this question.

I have not noticed any problems and my filters and nozzle are always relatively clean. I’m just wondering if there is any disadvantage to using old oil.