If you bought a brand new car ( petrol/diesel) and NEVER serviced it BUT keep all the fluid levels at the right level, how many miles would it last before breaking something?
In tests, the Americans have run cars to 100,000 miles with no oil changes and, apparently, no material adverse effects. Modern synthetic oils and fluids are quite extraordinary.
Would I try it myself? No! But I'm perfectly happy with 2 years/20,000 miles service interval.