The problem is, What is the definition of " a life time". Oil will always wear out as it is used in machinery. The lubricating propeties will become used up and destroyed over time. Gear oils usually use sulphur which coats the contact surfaces of gears but, It can't last forever.

I used to rebuild industrial gearboxes which ran using old 20w50 engine oil and when drained the oil was often like a copper coloured soup. This was fragments of the bronze from the gears but, They were supposed to be filled for life.

If the life of the transmission is expected to be equal to, or less than the transmission lub then that is the life of the lub, unless you decant it from a knackered gearbox into another one.

I believe that sound engineering reason for changing oil is "on condition". Chances are that measuring the condition of an oil would be more expensive than replacing it for average joe. A manufacturer would then be expected to specify a point at which a component (oil in this case) would cease to meet its desired performance (its initial performance may be above expectations, which then yields with time but is still functional). If this component's predicted failure point (plus a measure for tolerance) is after its major asset's anticipated failure point, then why maintain it?

"......don't mind me"

I don't mind you, but I don't like people peddling outdated or uninformed opinion as fact.

I don't quite get the bit about the oil refinery.

So do you think VAG transmissions are built to fail?

The notchiness that the OP is experiencing could just as well be down to wear in the selector linkages

Edited by Ordovices on 11/10/2013 at 17:12