This might sound dumb, but try cheap rump roast fluid. I used 80w90 out of a 5 gallon pail a buddy had. It was gl4+gl5 rated, smelled like hell. It made my trans so quiet I found out I needed a pilot bearing lol.
A little OT here, but I should add that I pressed these into service this summer while doing the two H6 HG jobs. In both cases at least a few of the 60+ timing cover bolts (small Allen cap screws) were messed up, and after trying and failing with an assortment of internal extractors, these were the ones that worked.