Gear change "tremble"

[Rossi#49]

I have a 2013 XF 2.2D Sport with 57k on the clock. On motorways in D mode on cruise control at 70 or so when coming to a slope in the road I am feeling a slight trembling before the box drops down a gear from 8 to 7 and the tremble stops. I can replicate this when not on cruise by hard acceleration from 70 in 8th, until the box drops to 7th. Less obvious in S mode, but still there. In normal driving below about 65 mph there are no issues at all. There is no change in engine tone at all ie the sound I'd expect on acceleration is there, no stuttering or similar. No movement or vibration on the steering wheel so I am thinking transmission? All suggestions welcome? The start of a failure of the torque converter? A sign the transmission oil needs checking or changing? Thanks in anticipation.

[andypryce]

Hi, what’s your mileage? As car is 9 years old first thing I would do is change gearbox oil.

[Rossi#49]

It 57,000 on the clock

[andypryce]

I would go for oil change as a starter then yes, as it’s relatively inexpensive and will cure at least some gearbox issues.