Hi Aleks,

There is no general guideline for fluid longevity because it will typically depend on the individual's calibration practices. Some take a sample of fluid, put it in a cup, then calibrate with that cup. Others will dip the probe directly in the fluid. The later opens up a higher chance of cross-contamination, thus giving the fluid a shorter life span. Personally, I replace my fluids after 3-5 calibrations. If you're starting to question the fluid at 1 year old, I would recommend replacing it for a fresh bottle.