Which auto oil?

My next job is to change my automatic gearbox oil. I have access to a ramp and it doesn't look hard. But 2 quick questions:

Would you just do the oil or the filter as well? The filter is cheap enough at £15, but I've never done one on any other car. Is the filter something unique to Landrover or 4x4's? Mine has done 97,000 and I've no idea if the oil or filter have ever been done.

Also, what oil? Halfords (where I'll get a discount) has Castrol Dex 3 at £9/litre. Ebay has Millers at £37 for 5 litres. Can someone recommend a type?

tnx

Nik

Go to a good motor factors any transmission fluid that meets the spec will do. You should be able to get 5 litres for less than £20.00. Do the filter as well you will need i think, a good T27 torx socket.

Good point from Wammers about the T27 torx socket - otherwise you'll be cursing when you come to undo the final screw on the pickup pipe!

I usually try to buy my replacement filter a week or so before I intend fitting it - that way I can lay the new sump gasket out flat for a week (it's usually coiled up in a box to post, and if you're flat on your back trying to re-fit the sump, it just makes life easier). Given that you have access to a ramp, this should be a piece of ****

I buy my ATF from Broughton Lubricants - reasonably priced for Castrol ATF TQ DIII (20l for £76.20 +VAT or 12x1l for £53.52 +VAT). As with most things to do with the Rangey, I assume I'm going to do them at least once a year, so might as well stock up.

The gearbox holds around 9l of ATF, but it's only possible to drain around 4 or 5 litres at a time. I usually do a fluid and filter change, then drive it for a week or two, then change the fluid again - that way I reckon I've at least changed most of it.

One final thing - I usually check the level on mine again the day after I've changed the fluid - make sure the engine is idling and you've shifted through all the gears to get the correct level.