Keith B.

I've got Toyota red coolant, which I pre-diluted with distilled water. It's been sitting in a sealed container for about three years. Can/does the stored, diluted coolant go bad or degenerate somehow?

peow130

Does it smell like fish?

stackedyoda

I know oil has a shelf life of 7 years, so I wouldn't think 3 years would be bad for coolant.

sb5walker

It's possible the corrosion protection chemicals might break down some in 3 years. I would test the pH. Mixed 50/50 with distilled water, Toyota Red should have a pH of 7.3 when measured with these papers:
http://cgi.ebay.com/ws/eBayISAPI.dll...m=110701564252

And test the specific gravity with one of these:



The freeze point of a 50/50 mix should be -34 F, but since antifreeze is not all ethylene glycol but contains about 3% corrosion inhibitors, the freeze point may be closer to -30 but shouldn't be much above.

If the pH and freeze point test okay, it's probably okay to use. But I would check the pH every six months or so, and replace when it gets to 7.0. You might consider using it for just a year or year and a half, instead of the full 2 years.

Keith B.

Thanks for the replies; I'll probably mix fresh to get the longest service life. Flushing coolant is a furtive, secretive clandestine activity here at the apartment complex--someything to be done as seldom as possible.