As much as I love Hylomar and hate RTV, if there's a possibility of some larger gaps remaining, I'd go with the RTV. Hylomar fills imperfections perfectly, but it's not intended to fill gaps.
--------Robert OK Don wrote:
$150 of wleding and de-warping later, I'm about to install the repaired oil pan on the 300SDL. (I'll post photos later). I had to clean off a LOT of black RTV sealant - no fun. The machine shop thought they got the pan "pretty flat - the bolts should pull it up the rest of the way". So, I think I need to use a sealant - the question is, black RTV or Hylomar???