No need to add an oil additive as long as you use good quality fully synthetic oil of the right spec and change the oil and filter regularly, but no real harm done by adding a quality additive either, the small amount won't make the oil viscosity too high.
That tube in the middle oil filler hole is the oil extraction tube which goes nearly to the bottom of the sump. You stick a tube over it (must be a tight fit to create a vacuum) then the other end connects to a vacuum pump/extractor, and you pump the old oil out. Pretty much all the JLR dealerships do it this way and have done for years, a lot quicker and easier than dumping the oil via the sump plug which necessitates removing the plastic under-tray - lots of bolts and screws!
Plenty of debate over whether the vacuum pump extraction method leaves a little too much old oil residue in the sump compared to the old fashioned sump plug method, but I suppose if it's good enough for the JLR dealerships (and obviously it was designed into the engine from the get go) then I suppose it is OK.

 

Get a suction pump, so you can make changing the oil a much easier job. I use the one from Griots that is really for brake jobs, but works great for the engine oil too, so I have both covered in 1 device.

 

OK...I see its been several months since the last post on this thread, but does anyone know the oil quantity needed at oil change? I rad somewhere it differs if you are draining at sump drain plug or extracting out. I have the 2.0L turbo. I think I read also 5W-30 Castrol Edge extended performance. I see they actually make Castrol edge professional (jaguar edition) but I can't find it anywhere and I'm sure its an arm and a leg. So I figure I will just use the edge extended performance. Just wondering how much oil I need to buy. Thanks everyone!

 

Can't help you on the 2.0 but it should be in your owners manual if you have it as well as the spec you are to meet. At least with the 3.0 the edge extended performance doesn't specify that it meets the required specs (could possibly void any warranty you have and might not actually do what it is intended to do). You can get professional from some Jag dealers and online sellers and you are right it isn't exactly cheap.

 

British Atlantic is my hookup for the Castrol Edge Professional. I haven't found a better place to buy from.