Freelander 1 What do you recommend?

Morning all.
The Engine is the BMW M47, TD4. it's done 350 thousand miles. Touch wood, and it still pulls like a train. it's not been stripped it's original milage.
What Engine oil, would you recommend? And Should I use an additive with the oil at it's next oil and filter change

I don't see any need for additives.

Your oil viscosity choice depends on the usage and environment. I'm using 5w-40 fully synthetic oils because we have nordic winters. There are many viscosity options listed in the manual.

The manual also gives you the oil spesification which would be ACEA A3/B3.

If its done 350k miles, I think the obvious answer is to put the same stuff back in!

The older an engine, the more important it is not to skip or lengthen service intervals

Use whatever is recommended, not the cheapest stuff 'because it's an old car'