Engine flush

Cheers Lads for your input but just done the change but added an off the shelf engine flush from millers oils uk.
Definately noticed the old oil was thiner in viscosity on dropping due to the flush.
Anyway just doing the auto transmission and looking for the refill capacity i think it's 5 litres ish but will do a search to make sure.
Cheers,
PB

Nice bit of info but I do have a question as to how the gears are lubricated

Thanks for the heads up on the ATF.
At my last place of employment one of the shift engineers told me used to add diesel to the oil as a flushing agent I was very supprised and thought he was mad which he replied " been doing it for years without any problems"
I think the ratio was about the same as the atf for about 15mins at idle.
Never tried it myself though