Newbie with 4.6IS questions!

[Sniffer]

Hi Guys,

As someone who has acquired an E53 4.6IS X5 in the last couple of months I have been lurking on here a few times since

The vehicle in question is a two previous owner 2002 model in Estoril Blue - I`ve always wanted one and as it ticked all the boxes (AWD for the harsh Canadian winters, Winter tyres on smaller 18" wheels of the same style, desirable model, good colour, good history - previous owner took good care) I took the plunge

I now have some questions:

I find the ride "harsh" - now I know that the 4.6IS was breathed on by Alpina to make it more sporty but the ride is not comfortable IMO - I definitely expected better considering it has air suspension, my buddy had a Range Rover Sport with standard air suspension and the ride was amazing - is this something X5 owners simply have to deal with or is something wrong?

I find their to be a steady "drone" or "whine" (which increases with speed - noticeable from 60KM/H up) which I initially attributed to the standard 20" tyres being almost worn out but after fitting the smaller 18" with the softer snow tyres the noise is still there - is this normal or should I be thinking gearbox (which shifts just fine)/driveshafts/wheel bearings?

The vehicle has lost a little coolant (is this normal - I`ve NEVER had to do this to any vehicle Ive owned before) and I`m about to top it up - can I use this antifreeze? Clicky Ive heard horror stories about using the wrong type and the effect it can have on certain types of metal, I also remember someone saying that mixing two different types (specifically colours) can neutralise the antifreeze effect - is this true or am I worrying unnecessarily?

What the general consensus for service intervals on these vehicles? Ive always looked after my stuff and this vehicle will be no different

Thanks in advance!