'' The new Volvo pumps use a stainless open impeller which may not move as much coolant, or so the debate on the design went. ''

Volvo now use open SS impeller ? This is shocking. I had many many years ago overheating problem at idle on the 1982. The pump had open propeller. Problem was fixed by using a Volvo pump with closed impeller.

'' What brand red coolant? I know you must not use orange-color coolant in redblock Volvo. ''

I use Dexcool. On the container it says: GM approved and 5 years protection against rust and corrosion. I have used this for more than 10 years. It seems to keep the radiator cleaner, less greasy let say than the yellow type I was using before. I particularly feel the heater gives more heat on a very cold day.

I do not pressurize the cooling system since summer is not that hot here in north east. 430k km and 34 years original heater core that I don't want to fail most of all.

Good subject.