Why is it necessary to change vehicle oil regularly, and not just change the filter and add new oil as needed?

Question

Why is it necessary to change vehicle oil regularly, and not just change the filter and add new oil as needed?

In: Engineering

Answer 1

There does appear to be a US obsession with changing oil.

Almost all oils are synthetic oils now and behave very differently to traditional mineral oils. They last longer.

Engines are machined to fit together much better than they did in the old days.

So you don’t need to change your oil every 5000 or 6000 miles. Most cars tell you when to change the oil.

What I would like to see is a properly controlled study between regular oil changes and changing oil when the car monitoring tells you to. Only this way will we really know if we should change our oil more often.

But with more electric cars on the road this becomes a moot point.