ZF 'Sealed for life' Autobox oil change

[buzzer]

I changed the gearbox oil on my BMW 728i at 80k miles, the again at 110 k and again at 140k. The first change also included a filter and therefore sump off change. It's not difficult to do. I used a magnetic thermometer on the sump to check the temperature was in tolerance.

The oil was a bit expensive but as people have said, cheaper than a new box. When I sold the car, the gearbox was still perfect. I actually used Audi oil for the A8 which used the same gearbox and was a lot cheaper than the genuine BMW oil. It does need to be the right oil though... Many gearboxes have the correct specification oil on the plastic bung on the bottom if ifs still there.

There is an excellent automatic geaerbox specialist in Wolverhampton called Penn Autos. The owner is a real petrol head called Andy Frost, who is a drag racer... They really know their stuff on auto gearboxes, but don't get him started on drag racing, you will be there a while!

[grand cherokee]

with regard to the sealed for life gearbox oils - does there appear to be any correlation/connection with RR gearboxes often failing between 90 - 120K miles?

which just happens to be out of warranty 99% of the time?