Drain the synth. Refill with 10w40 diesel dino oil plus a quart of dexron and run it for a couple hundred miles. Drain and refill with synth and report back.

Synth leaks easier than dino, so it goes past ALL seals and gaskets easier. The dexron will soften and swell the seals some which will delay the need to do a top end teardown. An added benefit is the high detergent level in the dexron which will clean some of the crud and sludge out.

Not responsible for advice not taken...