MY RRSport is 3000 miles old.
Any additive useful in oil ? 2010 TDV6 3.0 HSE Santorini Black Tan Full Leather

Don't!
Just use a top oil (i.e. M1 0w-40), these have all the right addivies in them. Playing arround with others will only upset the balance. RRS SDV6 HEV Dynamic
XKR 700 BHP with Twin-screw and LSD

Mobil grade is the best one ?
Do you typically refill oil from time to time ?
With my Jaguar, I never had to add anything in between normal maintenance, in 8 years.
My wife's BMW sucks one liter every 600/700 miles. BMW deems it normal.  2010 TDV6 3.0 HSE Santorini Black Tan Full Leather

I have done about 8k miles on my RRS so far and I keep checking oil level from time to time, still no need to refill it. Vadim A.

Vadim, yours is petrol, so you'd not expect it to use oil really.

However, our smelly oilburners may need a drop, although I've done just over 3,000 in mine and the oil level is fine. See http://www.lonelyjanet.co.uk/rrs.html and find "187-193 Fluid level checks"
It says "V6 Diesel engine: Use only 5W-30 oil meeting specification WSS-M2C934-B only". Land Rover recommends Catrol oil.

I wonder if oil usage in diesels is related to how much you rag it? L405 P400e Autobiography (MY2020)... Silicon Silver / Espresso
RRS TDV6 HSE Lux (MY2011)... Nara Bronze / Arabica - now gone!