[old_master]

GM recommends Dexcool cooling systems to be flushed every 100,000 miles or 5 years. In the real world, every 75,000 miles or 3 years is more like it. If there's a leak, fix it; don't put a "band-aid" on it, (that's all the pellets are for). No need for them, he's trying to sell you a "bill of goods", totally unnecessary, and not recommended. Very important: DO NOT change over to the ethylene glycol, (green antifreeze); it will ruin the seals in the water pump, among other things. There are a lot of shops and back alley mechanics that are way behind the times when it comes to technology. The entire cooling system, (water pump, radiator, heater core, block, gaskets, etc) was designed to use a 50/50 mix of Dexcool and water, use it.

When flushing, remove the thermostat and all hose connections. Flush each component, (heater core, radiator, and engine block) in both directions on each hose until the water comes out clear.