Thought I would change the oil in the auto gearbox of my V8 Disco 1 which I drained 4 litres out and then put 4 litres of new ATF Dex2 back in. Some people have spoken to since said I should do the filter as well. Do I need to change the filter now before running it or would it be OK to run for 500ish miles and let the new oil dilute the old oil left in the torque converter then do another oil change and change the filter then?

Looking on other threads there seem to be a variety of opinions, some say you don't need to change the filter at all, others say you must because the new oil will stir up the crud in the gearbox and cause problems.......

Appreciate your advice

Yesterday i checked the gearbox oil level and noticed it was high so drained down to max level on dipstick. Drained nearly whole litre out!! Why would this be - i took 4 litres out and put 3 back in and its full??

GeraldL said:

Thought I would change the oil in the auto gearbox of my V8 Disco 1 which I drained 4 litres out and then put 4 litres of new ATF Dex2 back in. Some people have spoken to since said I should do the filter as well. Do I need to change the filter now before running it or would it be OK to run for 500ish miles and let the new oil dilute the old oil left in the torque converter then do another oil change and change the filter then?

Looking on other threads there seem to be a variety of opinions, some say you don't need to change the filter at all, others say you must because the new oil will stir up the crud in the gearbox and cause problems.......

Appreciate your advice

Click to expand...

if oil you drained out was reasonably clean its not imperative filter is changed or cleaned every time you change oil ,the fresh atf filter will be sitting in cleans any lacquer of it its a mesh screen not std type filer most think of,regular change ie once a year is preferable, a full change isnt necessary unless oil is contaminated in which case box is suffering,in any case autos dont produce crud and debris unless failing, over the years valves and other components get lacquered, atf is very detergent too much flushing with new oil can shift too much lacquer and cause issues with gear change etc, if oil is black a clutch pack is burning out and its only a matter of time before a rebuild ,if its brown change oil twice with a short run inbetween ,if its reddish just change once the 4.5 litres,

GeraldL said:

Thought I would change the oil in the auto gearbox of my V8 Disco 1 which I drained 4 litres out and then put 4 litres of new ATF Dex2 back in. Some people have spoken to since said I should do the filter as well. Do I need to change the filter now before running it or would it be OK to run for 500ish miles and let the new oil dilute the old oil left in the torque converter then do another oil change and change the filter then?

Looking on other threads there seem to be a variety of opinions, some say you don't need to change the filter at all, others say you must because the new oil will stir up the crud in the gearbox and cause problems.......

Appreciate your advice

Click to expand...

with out knowing the history of the car its unknown.... the transmission specialist should have pointed this out above
you may not need to change the screen filter but its good practice to remove the pan and inspect regardless if your doing a full flush or a fish tank change ... and this also give good opportunities to clean the magnet and pan

when you checked the level and found it reading high had you done the correct way to check the gearbox level.?
that is, with the engine running, cycle through all the gears, keep engine running and check level carefully.
If you checked with the engine off you would have a high reading.
If you did it correctly, my apologies.

Jim A
2002 Disco 2 Td5 auto
1996 Disco 1 300Tdi auto(gone)

Why any one would after disconnecting the 'cats' electrical supply's then dropping the exhaust Y pipe with both cats, then removing the chassis crossmember and then only removing the gearbox pan for inspection and cleaning and then reinstating everything including replacing the Y pipe gaskets but failing to replace the filter is beyond me