[masraum]

Originally Posted by beepbeep

Dot 3 is slightly less hygroscopic so manufacturers can lower servicing costs by replacing it less frequently. Other than that, it is worse in every other way than DOT 4.

It is like fitting thread wear index 500 tires to a car. They last longer while having bad performance.

Originally Posted by David Inc.

I guess if you're making a boring, light, economy car, stable over good is probably a good idea.

I'd say that 1 car in a million EVER over the life of the vehicle gets it's brake fluid changed/flushed. Yes, folks here on the board probably do it fairly often (by comparison) and track folks. But my guess is that the avg Joe and Jane NEVER do it. The only time it gets done in most cars would be if there's a problem that causes the fluid to leak out, or if the fluid is bled enough that it's changed through bleeding. But I suspect most bleeding results in just some fluid being changed, not all of it.