When the every 3000 miles became a standard the filters were not as good, the oil additives were not as good (oil itself doesn't wear out but gets compromised by various particles [metals from the engine, dirt from the air intake system {another filter that you may need to look into using a better than factory one}. condensation {which, in conjunction with combustion products, forms acids which first attack the softer metals such as bearings and which filers do not filter out}). Metals is true from wear in the final drive (which also may be part of a manual transmission/transaxle), metals & various softer materials which may clog valve body channels, are the problem in automatic transmissions/transaxles). All engines, transmissions, transaxles & final drives are vented to the atmosphere. If you see condensation on your vehicle, it is also in all of these things. This is why if a vehicle only takes 10 minute trips with time to cool down, it will have way more wear than ones that have much higher mileage.
So in addition to my annual oil/filter (if I change the oil, I also change the oil filter) changes, every 3rd time I do an oil change, I also change all the other fluids (including the antifreeze [and use distilled water if I have to mix it with water {to avoid electrolysis, which causes internal erosion of metal parts, caused by particulates in the water}].
With this regimen, even my highly tuned/modded cars have gone long times. Most of my vehicles have lasted 20 years & 200-300 thousand miles before I sold them (still in driving condition). Only one (a 1972 Mustang with a 351 Cleveland & FMX automatic), needed an engine & body restoration when I sold it. But it had well over 300,000 miles. I got it in 2003 & sold it in 2012 and it had a history of abuse.
