2 questions about 8 3/4 sure grip

Hey guys I have my new 8 3/4 all opened up and ready to go back together with good gaskets and all. I am wondering if there would be any problems with using full synthetic gear lube in it. Its a 489 sure grip.

The other question I have is how much end play should be in the drivers side axel? I understand how to adjust the pass. side end play but when I grabbed the axel to pull it out I noticed that there was maybe a 1/16 maybe more, of end play on the DRIVERS SIDE which does not have an adjuster. Hope somebody tells me its an easy fix!
thx guys.