I had a coolant leak in my 2011 RR SC and need to add a few gallons of coolant and may do a full flush. What is the correct coolant to buy from the local auto parts store? Every time I look it I’ve gotten confused as it seems unclear what brands meet all the requirements. Previously I’ve just bought from the dealer when I only needed a little but that’s a pretty pricey option I’d like to get away from. Current coolant color is orange.

 

Antifreeze_Coolant_Timeline.pdf
This is a good starting point for the research.
The real meaningful difference you have to look for is what the coolant is based on. Is it just Organic Acid technology or Silicate Enhanced.
The Inorganic is for rather old engines.

In your case the engine is Jaguar AJ133 (AJ-V8 Gen III 5.0-Litre) so I would look for an OAT - Organic Acid Technology based coolant.

An alternative is waterless coolant made by Evans. Just make sure you use the "Prep" fluid the remove any water leftovers before filling it up.

Happy cooling!