Vg and pg don't really have much smell to me. Vg is thick and sweet. Pg is the consistency of water. If they appear to be fine, you can wick a rda and vape some individually to see how it tastes.

However, when in doubt throw it out. It's not that expensive to replace them. We only get one set of lungs.

Can confirm guys, mixed up a tank of the pg and vg, tastes and vape fine to me !

PG will stay good in a closed container for decades. PG is used as a coolant in HVAC in large chillers for buildings. That PG stays good for 50 years. PG is a humectant (collects water from air). PG goes bad when opened to air and collects a huge amount of water to were the water allows growth of bacteria. This becomes visible and smells like a swamp. But if left closed for most of its life, it stays just fine. VG is the same, a humectant. It too will go bad when it collects too much water. However since VG is a sugar alchohol bacteria grows easier than PG. It will become thinner, visible floating specks, and smell like mushrooms and dirt. If kept most of its life cycle closed to air to collect water, it will stay good for about 20 years. The first thing to go in VG is thickness and sweetness that will disappear and is ate up by water and bacteria.

PG should hold much longer than VG, if both don't come into contact with air and you store them in glass bottles in a dark, cool place. PG > VG

PG is antibacterial and it is used in lubricant to make it last longer. I'm sure there are many similar uses in the medicine or food industry. Correct me, if I'm wrong.

So, round a bound. I'd say, that if you keep your PG in 5/10Lb plastic canisters, it will last far above 10 years, while I'm not so sure about VG. Maybe 5-10 years?