What do u do/suggest with wooden whistles by Greenwoodpipes?.
Did you contact the maker? Isn’t that David Boisvert? He has a website.
Dave
The most common reply i ever get for wood is Almond oil - but dry the whistle first.
There’s another variant using olive oil as well - but with some vitamin E to prevent oxidisation - anyone got a good recipe? Or even a better formula?
The other thing I keep hearing is that different varieties of wood can be much more prone to moving and cracking no matter how well seasoned - for example Ebony has a bad rep for cracking, many of the acacias are renouned for cracking, but most of all: every timber will expand when exposed to moisture so keep it dry!
No matter who I ask, the only timber that seems to be universally recommended is African blackwood - the universal number #2 seems to be delrin.
I’d be so happy to find another wood as well regarded as Blackwood and Delrin 
I wonder if Dymondwood™ will stand the test of time here’s hoping.
Out of some 225 whistles that I’ve made,I’ve only had to repair cracks in 2 or 3 (if you don’t count the 4 gorgeous but finicky Snakewood whistles…). No particular wood in the couple I’ve fixed either.
By and large, I think the danger of a wooden whistle cracking is overblown (so to speak 
). Care is pretty much common sense: don’t subject the whistle to extremes of temperature, particularly heat. Leaving a wooden whistle in a closed car on a hot summer day is asking for trouble. Cold is not nearly as much of a problem, but if the whistle gets very cold, let it warm up SLOWLY in it’s case before you start blowing warm moist air through it. Don’t sit on it (NEVER leave the whistle on a chair or carry it around in your back pocket). That and an occasional oiling and you really shouldn’t have any problems.