According to EET Corporation's Antifreeze FAQ:
"Antifreeze concentrations higher than recommended levels can cause
problems including corrosion, water pump failure, and increased engine
wear. Increasing the concentration of ethylene glycol above 60%
actually hurts the engine?s freezing and overheating protection"
You will probably find a drain valve on the bottom of your radiator
that can be opened to remove the coolant. If not, you can drain by
removing the lower radiator hose. Either way, there is still a large
amount of the coolant in the engine and in the heater core that does
not get changed. If you want to remove all of the coolant you should
take your vehicle to an auto shop to have the coolant flushed out.
Be aware that antifreeze is toxic. Keep pets and children away.
According to the FAQ referenced above, "every year about 10,000 cats
and dogs are victims of accidental poisoning by ingestion of
antifreeze". Antifreeze is also harmful to the environment and must be
disposed of safely. Your local waste disposal facility should be able
to take it, and in some areas you may be allowed to dispose of small
quantities down the sanitary sewer. For example, according to the
Minnesota Pollution Control Agency:
"businesses that generate less than 600 gallons per year of waste
antifreeze may discharge it to a sanitary sewer system PROVIDED it is
allowed by the local wastewater treatment plant"
I trust this provides the information that you require.
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too much antifreeze