small oil leak vacuum pump bottom NUT

[jpliddy]

hi all i have tried to stop this leak few times now fitted a brand new NUT to the bottom fixing on my vacuum pump this nut replaced the brand new genuine volvo NUT so still it weeps i have removed the NUT clean the area dry and a smear of hylomar blue but still it weeps it looks like oil travels along the thread of the anchor but it could be getting out on the surface mate of the NUT.!! the top NUT is perfect dry . any more advice on how to fix it