Tim, I think we have had our differences on what constitutes an oil "seal " here before.
What exactly was replaced? The "O" ring around the main oil gallery dowel? The blanking plug in the front of the camshaft bearing carrier? The gasket between the camshaft bearing carrier and the crankcase? ( This gasket MUST be specifically for the turbo motor - if it's for any other CX500, then it WILL leak oil profusely). The "O" rings on the fittings at either end of the oil-feed hose to the turbocharger? The clips on the oil feed hose? The oil feed hose itself - and its heat-shield? Any scores/ scratches on mating surfaces?
All these components - and maybe more - are suspect, when an oil leak is experienced down the front of the motor's crankcase.
Tim, If Dan's copper gasket is even minimally thicker than the standard one, you WILL have trouble with the standard Honda "O" ring - it's really too small in cross-sectional size to do a proper job - even in its new shape. Go find one that has about 0.5mm greater cross-section size, and use that - it must be a snug fit on the dowel.
I'll be digging in my spare turbo bits today, so I'll have a look at any other likely causes.
Tim, Get Steve to check the blanking plug in the "bottom" of the almost vertical oil way that feeds oil up to the turbo fitting - it may have become loose after manufacture.
If the "O" ring is still flexible, then it should show only minor flattening. As you can see, that "O" ring gets no help from the gasket - it's really "on its own" with the oil pressure inside it expanding it - not a very brilliant piece of Honda engineering.
It should be between TWO channels - one in the block, the other in the camshaft bearing holder - not sitting on a planar face on the block.
Tim, Another thing to check is the two "wells", into which the two "O" rings on their fittings, slot into - there may be some score marks inside them. It's also possible to distort either or both of those "wells" if you don't line up the oil-tube fittings before you tighten down the bolts that hold the fittings. I'm not talking about the grooves that the "O" rings go into, ON the fittings - I'm talking about the holes that the fittings themselves go into - one on the turbocharger, the other on the camshaft bearing holder.