“I haven’t brushed my teeth, but I don’t have a cavity - so I’m good”.

Don’t get me wrong, my “fun” car (an old, beat up Jeep) is going on 2 years with the same oil (I barely drive it), but I known I need to change it soon.

Oil degrade with oxygen. Every time you drive that car, the oil are being re-oxygenated and continuing to degrade (along with being exposed to combustion byproducts).

Also, the type of wear you get often isn’t noticeable until it becomes catastrophic. In my case, a 30 year old car that’s already on its last legs “catastrophic” is more like “time to finally drag it to the scrap yard”.