So I’ve got two different sets of instructions here, one from the bottle of Prestone Super Radiator Flush and one from the guy who sold it to me, who I really tend to trust as he seems to know what he’s talking about.
In a nutshell, here they each are
METHOD ONE
Car off and cold, remove cap, open cock valve, put garden hose in mouth of radiator. Start engine, adjust garden hose flow so it’s refilling the radiator at exactly the rate it’s draining. Run engine like this until the liquid draining out is clear water. Close cock valve, remove garden hose, pour in bottle of Flush, put cap on. Run engine until it gets to normal operating temperature. Turn off car and wait until engine cool. Remove radiator cap, open cock valve, put garden hose back in, and just like before, run engine and flush the system until it’s clear water coming out. Turn off engine, leave radiator cap off and cock valve open so it can drain completely. Close cock valve, and fill radiator with coolant-water mix.
METHOD TWO
Engine off, radiator cap off and cock valve open, drain the radiator. Close cock valve, pour in bottle of Flush and fill radiator with water. Put on cap, and run car with the heater on maximum hot temperature for 10 minutes after the engine reaches normal operating temperature. Shut off car, let engine cool, remove radiator cap and open cock valve and drain the radiator. Close cock valve, fill with water, put cap on, run for 10 minutes with heater on full blast after reaching normal operating temperature, like before. Shut down car, let it cool, remove cap and cock valve, drain radiator. Close cock, and fill radiator with coolant-water mix.
They both involve draining the original contents, running the engine hot with the Flush and water in a pressurized system, draining that out, and filling with coolant. The key difference is whether to use a garden hose and do the flushing with the engine running.
Which method is the way to go? Is it important to use a garden hose to flush it out, is it important to run the heater, both, neither? Do you use some other Method Three?