help needed with diesel leak

[Poodle]

Theoretically yes, but it's made of cheap plastic so the seal doesn't last very long, if it ever seals at all, and tends to deform the first time you do it up tight. As you say, recommendation is that it's changed every time it's taken out, but they're fine for multiple uses in my experience, the o-ring seems to be perfectly capable at sealing by itself.