Depends on the knife. Something in a "low grade" stainless with a high chrome content like 440A, 420J2, 425 or whatever won't be "eager" to rust. The top "stainless" steels like ATS34, BG42 or the CPM types might be a bit less rust-proof, possibly bordering on "tool steel" toughness and edgeholding (which is good) but as a tradeoff are barely stainless. D2 is "just on the other side of the border", it's a tool steel that is somewhat reluctant to rust but ain't considered "stainless".
Also, any single steel's rust resistance *and* other qualities will vary with the heat-treat. And finish - bead-blasted often equals "loves to rust". Hardness often equals rust resistance regardless of steel.
If you do a thin oil coat then sheath a stainless blade in a DRY leather sheath and keep it that way, it should be fine...but there's no guarantees.
Jim March