An even more serious one involving Stans tubeless sealant...

IMO, there is no real timescale for changing the fluid, there are too many variables that can effect it, stuff like how many puncture have you had, the temperature, how much did you put in in the first instance and what size of tyres do you have. All those things can effect the fluid lifespan. Like you say, the best thing to do is just give your wheels a good shake every now and again.

PS if its empty, buy a small syringe fill it up (use as many times as you like), take out the valve core (obviously after you have deflated the tyre) and squirt the new fluid through the valve, much easier than taking the tyre off and you also don't have to take the wheel of the bike that way.

Cheers lads, Euan I got the syringe to go tubeless in the first place - like you say loads better than faffing about taking tyres half off. Worked well with the syringe.

Looks liked it's the shake and bake method then.

If I was tubeless, I'd just change it when the tyre began to lose air..

Does it give that easily then?

I always thought it would lose slight pressure over time kinda thing rather than just let go.

Do you have to empty the old stuff out first?

I just top mine up but I am always fannying about with tyres so they are on and off quite frequently. The stuff does go off in the warmer weather and it tends to dry up into a spikey ball. It isn't a hardship to pop a bead now and again and just check.

Tubeless is great. 

I wouldn't regard any tyre system as fit and forget. Some people chose to fit superstars bling, I fiddle with tyres.... One will affect the performance of the bike and the other won't.....

hey ste,nice to see you.it`s funny you should mention a dipstick when referring to a post where hammy`s  involved