Hmmm, I wonder... Being able to smell it means that is it "emitting" volatiles that our noses are sensing. I suppose in theory, once enough of those volatiles have left the bottle into the atmosphere it could become ineffective as a friction modifier and we would be left with mostly just the...
I recently changed my differential fluid. I had a leftover unopened bottle of XL-3 in my garage (had likely been stored there through a couple of winters). When I opened it and added it to the differential I noticed that there were lots of "lumps" or "gels" visible on the walls of the tubing...