I replaced my water pump 25 mo ago, and since I have pets, I had the mechanic
put the Sierra Anti Freeze in when he re-filled the system. I have had no
trouble yet. I probably have driven only about 20k miles, but it has been
through freezing weather both intervening winters (mid 20's - not too cold),
and a couple of mid-90 summer days without problems.
Regarding the toxicity. About 6 months ago, I noticed an article my mechanic
had posted regarding the Sierra (I think it was by one of the ethylene glycol
manufacturers) that it too is toxic, in part because of the additives such as
corrosion inhibitors, etc., citing a few onces to be toxic. Thinking of pets
licking up spills, that beats ethylene glycol containing anti-freezes whose
toxicity is measured in spoon-fuls. The article though made another
interesting point, as regards disposal of the stuff. The industry has in
place systems for handling ethylene glycol that is drained from coolant
systems, but not (yet) for propylene glycol. In states such as Washington,
which regulates the disposal of such materials, this may be a problem if
having work done that entails draining the coolant system.
Larry Schadt 5kCQ, Olympia Wa.