Since rebuilding the engine on my son's D2, we have had a persistent loss of oil.

It is not burning off (no smoke), but rather leaking off the back of the motor -- the cross member under the tranny is always covered in a light coating of oil, but there are never any pools of oil on the ground when it has sat for a while. And the rocker covers are well sealed and bone dry.

I have replaced the oil sump gasket -- twice. The first time I used hylomar, the second black RTV. The RTV seemed to help a bit.

Both times I inspected the rear main seal and cruxiform seals as best I could with the sump off, and as best I can tell the leak was not there. I cannot see the rear camshaft cap, but we hylomared it and pressed it in correctly I think after we got the block back with new flanged liners.

As I am at a loss for what to do next, I was wondering about the metal disc "spacers" that are molded into the sump gasket.

I assume that they are there to keep from over-tightening and crushing the gasket, but has anyone had any experience with just popping those spacer discs out, filling them with RTV and torquing down the sump that way?

 

Right, those are to keep you from squeezing the gasket out by over tightening the bolts, just like on the valve cover gaskets.

You obviously know what you are doing since you've checked the cruciform gaskets and rear main seal, and added hylomar (blue, I guess). If the engine has been redone with new bearings and you feel good about the rear one I'm stumped, too. Of course, it is most likely the rear seal but we both know what a job it is to replace.