Update (just in case anyone else is thinking of doing this) - I couldn't find anyone who would do a flush (within 25 miles anyway), so I have ordered 20L of Texaco 7045E from Watsons Oil for £66 delivered and will be starting the "multiple oil change" technique this weekend !

I'm also going to try to siphon the oil into the gearbox by placing the 20L container on the passenger footwell and just use a bulldog clip on a length of plastic tubing at the gearbox end to control the flow ...

The gearbox does not appear to be exhibiting any nasty symptoms currently (touch wood), so I am hoping to prevent any in the next couple of thousand miles !

Keep us updated on the how it went

That's a good price for ATF

Done - and I was surprised at how easy it was.

After draining very black transmission oil into a bucket for about 30 minutes I got 6 litres out, with some sludge on the magnets in the pan. After going through each gear for 15s whilst stationary and running the engine to get the temperature up it took another two top ups to get to the right level at 43C. Since I was lacking any sophisticated workshop pumps, I just siphoned the ATF with the 20L container standing on a workmate at the side of the car.

Apart from burning my thumb when checking the levels after a 10 minute drive, the biggest surprise was how quiet and smooth the gearbox became ... I should have done this 10000 miles earlier ! Thanks to everyone for the advice.

Just got my filters today and ordered the same oil from Watsons so I will be doing mine next weekend.Fortunately I have the correct tool as I purchased it to change the oil in my TD5 Defender.Keeping my fingers crossed as the car has done 127k with no gearbox fault symptoms - yet !

What is the correct tool?

A T45 Torx bit for the drain plug or a 17mm spanner for the fill plug - I found out at the last minute that my T40 was not the right size

Draper 500ml Oil Suction Gun

Designed for use on vehicles and machinery such as gearboxes, axles, diff. engine etc.

Ideal for Gearbox/Diff refilling/top up on 4 x 4's

Supplied complete with flexible delivery tube 10mm bore, approx 12in - 30cm long.

All Metal Body and End Caps

Draper Stock No 47812 Part No A5/L

Ebay Number - eBay Item No. 130495757267