I had the car mot today and it had on as an advisory that there's rust underneath including the rear sills. Is there any point in having wax oil or dinitrol done

Impossible to say without seeing it. Jules

Depends how hands on you are I guess. A wire brush (use eye protection) and a waxoil won't break the bank and will do the car some good. FL2 MY10 TD4 GS traded in at 2 years
FL2 MY13 TD4 GS Current

I will have a scrabble underneath over the weekend to have a look

I thought the panels had some sort of zinc coating/galvanising.

My 2007 Freelander 2 has such good protection underneath, I have taken out headlights & wheel-larch plastics etc to check for any signs of corrosion as its 11 years old & so far have not found any trace.

My 2005 Mitsubishi Shogun underneath had no sign of any protection at all hence it was quite rusty. Where these vehicles are meant to go & with all the mud & water etc I would have thought that they should have had been given an ultimate coating of rust proofing.

Well I had a look and it's only surface rust. Why they flagged it up on the Mot I have no idea. There's a place in Chesterfield that does wax oiling they are going to phone me next week if they do it as I want is will have it done

When I bought mine last year I was shocked at how much corrosion there was on both sills and all wheel arches.
See here: http://www.freel2.com/forum/topic30091.html

If you can do it yourself it’s worth taking a week out to put it up on stands remove all wheel arch liners and plastic outer sills, clean off and waxoyl all areas. Pull the rubber bungs out wherever you see them to do the cavities as well. Be sure to check the tops of the suspension turrets, they will probably be quite bad as there is no protection from tyre thrown dirt.

Strangely the underside between the sills was clean and well protected from the factory. It’s bizarre the same protection isn’t added to the arches and sills. Derek Hill
2009 FL2 HSE TD4 Auto

I could do it myself but don't have the time. I am going to ask if this place in Chesterfield will remove the plastic wheel arches and do more or less what you have done.

Had the price today £225 plus vat remove the plastic wheel arches clean all off under and treatment they have agreed to email before and after I can then post on here

That’s not a bad price for the work involved. Make sure they also remove the plastic outer sills because inner metal ones will need attention I’m sure. Hope it goes okay.
I’d be interested to see the ‘before’ pictures to see how it compares with what I found on mine.
I suspect mine had a beach run or two somewhere as a lot of the dried soil I got out was very sandy. Nearly 3lt of it in total, crammed into crevices behind the plastic liners. Actually the front ends of the sills near the jacking pints were so full of soil they were totally clogged. I had to start getting it out by digging it with a screwdriver. Derek Hill
2009 FL2 HSE TD4 Auto

Well today was the day after dropping the car off, I had a phone call 4 hours later saying that they are not prepared to remove the wheel arch liners incase they break them. It was said that if I removed them they would then do it. So if I go to all that trouble I may as well do it myself. I will remove the surface rust as that's all there is paint with galvanised paint then wax oil. Bit of a waste of time and diesel so no point in anyone going to motor seeker in Chesterfield

Are Rustbuster close enough to you, (Spalding) they did mine about 5 years ago.

http://www.rust.co.uk/rustproofing-price-list/p512929

They take the wheel arch liners out but won't remove the door sill liners, which I think are worth doing as they get filled up with mud. They are easy to remove so might be worth asking if they will remove them or if its ok for you to remove them first.

Click image to enlarge

Click image to enlarge

Click image to enlarge

Spalding may be a bit far how do you remove the door sill covers6

As far as I remember, a couple of metal screws front and rear, then the plastic ones along the bottom. 
Hung like Einstein, smart as a horse.

Back in the old days when I drove Morris Marinas etc I used to paint the underside of my vehicles with old engine oil. This worked fine until we had some friends visit with a small white Scottie dog who came in one day with his head and back covered in engine oil as he had clearly been under the car. Poor bu**er spent about an hour in the bath whilst we tried a mixture of swarfega and fairy liquid to clean him up. We decided against using Gunk.  3 x FL1 2 manual + 1 auto
5 x FL2 4 manual + 1 auto
Now Discovery Sport P250 MHEV SE