Originally Posted by
WhyFi
Wow, that's a long time - I've learned to check my sealant every 6 weeks or so, it can be problematic otherwise.
Just check the level - put the bike on a stand, deflate the tires, rotate the valves to the 6 o'clock position, remove the core and use the dipstick that comes with the 8oz bottle. If it's low, top off.
On some deep Mavic wheels (Comete UST) the valve is actually a valve and an extender, in which case the dipstick method won’t work as the dipstick won’t fit through the tiny hole. Gotta pop the bead then to check (although not exactly a big deal).