AndyPants

I used loctite 5980 on my sump and it worked fine. I bought mine from Halfords - listed as black sillicone gasket maker/sealant thats designed for flanges for permanent oil contact. Even shows a picture of sealing a sump by the look of it on the box!
 
I did have to do it twice though, although that was mainly because I didn't have a good enough bead the first time. You don't want too much sealant, but equally it needs to be a proper bead. If the tube is hard to push it out then ensure you've cut the end cap off enough, makes it much easier than trying to skimp on sealant and having to crush it in both hands as I did!
 
Since doing it my VRS hasn't lost a drop of oil.