This is a personal thing I guess.
I have been using WD-40 for well over 2 years to treat and even prevent SLM.
I have had birds so damaged by these critters that I thought it was a hopeless cuase.
I have saved quite a few birds by treating them with the dreded WD-40.
The girls and I have a standing tolerance for each other. I run my fingers down their legs at roost time and the ones
that have the least of a hint of raised scales gets a squirt of WD-40.
I have a happy, healthy and vibrant flock of hens that run with their respected roosters every day.
I have TOO many roos and am working on rehoming the ones that the hens do not like.
My hens will reject any roo that is a rapist or a bully. They simply WILL NOT free range with them.
We all have been through this debate over and over, but i am sold on WD-40. It is easy to appy and not a messy ordeal.
So go use your pam, your pine tar, your light oils and vaseline. The goonie is out in the chicken barn spraying the dreded 'Stuff".
I am also SOLD on DE. The barn is cleaned and DE is apply every so often.
BTW, the roos get treated too, they just do not tolerate it so well.
In two years of having GUINEAs, i have yet to see one with a case of SLM (scaley leg mites).
My Guineas do a communal dust bath in the horse pasture nearly every day.