530d Auto Gearbox Lockup?

[CarPrintGuy]

I bought a 2004 E60 530D Auto recently and it drives great, but just wondering why the gearbox doesn't lock up in 6th when cruising (floor it in 6th and the revs rise more, relative to the increase in road speed).

If it did surely fuel economy would be better.

[MajorBeef]

From what I remember about the ZF6 can lock up the gearbox from about 15C. I recall mine used to slip like mad on really cold mornings - very similar to an old 325tds auto box - but then lock up within a few hundred yards.

If it’s slipping in 6th only then I’d suggest something is wrong. Have you checked for leaks? At that age I’d be wanting a gearbox specialist change the oil + sump anyway. Fresh oils could make a big difference.