Can You Use WD40 Grease For Leather?

you use grease when you are working with leather

so that might have lead to the question about bike greasers, like oil and lubcricants. 

but it is a big big no no - dont use the WD40 on leather, because its used to remove moisture from surfaces and not for proteticing leather.

Leather is a natural product and you want to keep the softness and strenght in the product for most durability.

You can use like fats and leather conditioners, and not a product like the WD40 because it might actually damage the leather instead.

i would go as far as to say, that if you got any wd40 on leather, you might go ahead and treat some of that material to make it last longer - with beeswax or something even better.