Oil drain leaks, stoppable?

[Mags]

I'm fed up with oil leaks from the sump cover, what am I doing wrong?
A few years ago I replaced all the studs that the sump cover uses and the nuts, domed type. I have an aftermarket sump cover with a large drain plug in the middle, I pulled this all off last weekend to clean the gauze and replace the oil. Replaced the gaskets etc and only tightened gently by hand (or so I thought) so as not to damage the threads, new copper washers, paper gasket but no gasket sealant.
I noticed the sump cover didn't seem very flat across the bolt holes either due to poor quality or ham fisted tightening in the past (by me) so I tried to flatten it out. When for a run, all good. Look back under the bus a few days later and I have a nice oil leak as usual, in fact I think more than I had before I took it apart!
What am I doing wrong? lack of sealant? bolts too tight? (I'm not sure the low setting on my torque wrench is right for 5 ft/lbs, it feels too tight for such small nuts so I do them with a spanner) poor quality sump cover?

Mags

 

[Moseley]

You’ve said it yourself, if neither surface is completely clean and flat, you’ll never get it to seal without using some nasty sealant - which you’ll never thank yourself for when you next come to remove it!

If you’ve warped the plate, the chances are that you won’t get it flat again, so buy a new one (can you get billet ones that are machined flat?) I have always had to use a little more torque than the book says to get the copper washers to seal, otherwise the odd stud still gets a bit of weeping dripping off the nut.


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[sparkywig]

If the sump plate or the sump mating surface isn't perfectly flat you'll get leaks.

 

[K@rlos]

Answered your own question.... it’s not flat, Only the expensive sump plates like CB performance or Jaycee are 100% flat, plus a bit of sealant always helps. And don’t forget to use a torque wrench, that way you won’t warp the plate or worse pull the threads in the crankcase. A basic 1/4 drive won’t be a lot

 

[Mags]

Thanks all, at least I'm not going mad.