The V8 Owners Forum -

I have Rover 3.5v SD1 motor circa 1980 and am wondering which is the most suitable coolant for this engine ?

Best coolant pure water.

But if you are in cold climate you need an antifreeze.
And most antifreezes also have inhibitors and lubricants for pumps etc.

Ian

Blue antifreeze - 50/50 mix with water.

Chris.

Thank you, I will go for the blue mixed 50/50 with water as often have quite heavy frosts during the winter

Very important to use the correct anti-freeze all year round - or an inhibitor to prevent corrosion.