Since your car has 80K miles, this is a good idea. When refilling, one challenge will be to run that coolant pump so that the tank can be filled and air can be purged out of that system.ДЈ. Further, the coolant heat storage tank (which contains hot coolant) can also be drained, and the associated coolant pump should be disconnected during this process so that you don't have an accident. The engine block also has a drain cock on the side that faces the rear of the vehicle. Under no circumstances should you risk using a 2-EHA based antifreeze with it's known gasket compatibility issues in your Prius - which rules out DexCool and Preston long life any color any make coolant.Д¬lick to expand.1.

The only place to get a Japanese style longlife antifreeze is the dealer, and given how hard it is to remove all the old antifreeze from the Prius, I would recommend staying with the Toyota 'pink' longlife antifreeze when your Prius hits the 100,000 mile mark. Only the Japanese make a HOAT based longlife antifreeze with no silicates, no 2-EHA, no amines and low phosphates (the Japanese have long used phosphates).

GM's DexCool has no silicates and no phosphates but has the dreaded 2-EHA that everyone else hates. The longlife HOAT technology variations that everybody besides GM went to contains silicates and no phosphates (European makers do not like phospahtes) - Ford's G-05 is an example. I would not worry about until the 100,000 mile mark. So, at 80,000 miles you still have 20,000 miles of life left in your antifreeze. The Toyota Pink is good for 100,000 miles/10 years and 50,000 miles/5 years afer that. Toyota switched to a long life antifreeze using a Hybrid Organic Acid Technology, and like all Japanese manufacterers they use no silicates and they do use phosphates. BTW, Preston long life any color any make uses 2-EHA. So nobody but GM (and Saab, IIRC) uses coolant with 2-EHA in it. There was one problem - DexCool can weaken certain rubber and plastic gaskets/hoses/parts due to one of the major ingredients (2-ethylhexanoic acid known as 2-EHA ). GM's version, brand name DexCool can last 5 years/150,000 miles. In order to get a longer life, GM lead the way to longer service life with Organic Acid Technology (OAT) antifreeze. When it was let go longer, as many consumers did, bad things could and did happen.

It did have one major drawback - a 30,000 mile 2 year service length. It was great stuff and offered very good corrosion protection. In the old days coolant was based on Inorganic Acid Technology (IAT) for corrosion protection.

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