change oil a year ago have not reach mileage for change should i change oil

I’m not a believer that oil actually deteriorates over time - I’ve always waited until the desired mileage occurs - the engine is tightly sealed much like an oil container - I do recommend taking a look at the oil level and it’s condition. Do you think dealerships / collectors ,etc, change oil in cars they own simply because they have been parked for an extended amount of time just ?