This jug of conventional green automotive coolant concentrate was opened years ago and then tightly closed. Now it has a slight "oil slick" appearance (note the sideways V pattern in the close-up) with quite a few small distinct transparent globules floating on the surface. I can't imagine that this was contaminated with oil after it was opened, yet it looks that way now. Could this just be the result of sitting unused for years? Can I still use this?
Coolant Contamination?
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If you are quite sure that no one messed with it, I would put the cap back on the jug, make sure it is closed tightly, and then shake it up really well. Then let it sit for a few days to see if the globules reappear. If no globules, go ahead and use it.
You are likely looking at some of the additives that have come out of solution from sitting and experiencing temperature changes. If they do not go back into solution, then either something unknown to you was added, or some of the additives might have degraded over time.
You are likely looking at some of the additives that have come out of solution from sitting and experiencing temperature changes. If they do not go back into solution, then either something unknown to you was added, or some of the additives might have degraded over time.
Good plan. Will give it a good shake and recheck in a few days.
Certainly. Perhaps even warm it in the sun first?
That's what I was wondering about. I'd be interested to know if anyone else is familiar with this "separation" occurring in conventional coolant concentrate, or if it seems highly unusual. I'd feel better about using it if others had observed the same.
Interesting, perhaps it's fine to use then. Probably will not use, as the globules reappeared after the fluid was shaken.
Update: I have now discovered globules and "oil slick" appearance in an open bottle of DEX-COOL concentrate as well. Having observed this in two open bottles of coolant concentrate (conventional green and DEX-COOL) I'm convinced this is not external contamination.
What is going on here? Has anyone besides eljefino and me observed this? Is this phenomenon limited to opened bottles of coolant concentrate? Is the coolant still usable even though the globules reappear after shaking?
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