I just picked up a 1996 XJS 4.0 and am catching up on maintenance and repairs. What is the consensus for the best antifreeze to use in the AJ16 engine? It looks like the green stuff in there but I am partial to Zerex G05 in my older cars. Just wanted to poll the group and see if there are any thoughts.

 

Hi Thorsen.
Maybe it is solution. I have no problem with overheating of coolant (see spec.). And when is coolant system all right, it is lifetime.

https://www.evanscoolant.com/vehicle.../classic-cars/

 

Worth a search on the XJS forum concerning waterless coolant. A lot of us, me included think it is a very bad idea.

 

After having issues with coolant crystalising in the engine, I am going "universal". My XJ8 has ran it now for the last 2.5 years and has no worry. No problems with mixing and matching the fluid. No flushing required. And the universal stuff is cheap as hell... Prestone from Honeywell.

That is what my XJ-S will be getting too.

People most commonly choose their fluid upon colour, which is the biggest "brainfart" you can do. The problem being: the colours aren't identical throughout the market. And they change randomly. My old C30 came with yellow coolant. Which was replaced with red stuff later and then again with blue stuff which turned brown in the end.

You need to know WHAT the fluid was in order to know what you need to top it up with. WHAT means what the chemical base is. Silicone based? Glycerene based? ...