best coolant for d24?

[v8volvo]

I will make another vote for Zerex G-05, similar to the above, not necessarily that it is the "best" but certainly it is good enough for these engines that are not particularly demanding as long as coolant is correct mix and kept clean, as ngoma said. To my mind the advantages of the Zerex are that it has some extended life properties (relative to old style green coolant that should be changed every couple years), has wide compatibility with other coolants in case someone accidentally adds something different, and is widely available at almost any parts house.

I think an argument could be made for various other antifreeze products out there (there are MANY, some of which promise extra long life, etc) but the real bottom line is just to use something you know you can get your hands on reliably and are comfortable with, meets the requirements, and is kept clean and uncontaminated with other fluids or incompatible antifreeze types.

On that point, if you are changing from another type of antifreeze, be sure to flush thoroughly with distilled water to remove all the old liquid, including from the radiator, heater core, and oil cooler if equipped. There is no dedicated drain point on the engine block, so best block draining is accomplished by removing the thermostat housing and flushing thoroughly from there.