For the first 500-1000 miles use 2 quarts of any 90W gear lubricant, because of the grease used to pack the needle bearings, EOS assembly lube, Permatex, break in metal, glass beads etc. We recommend changing the gear lubricant after the first 500-1000 miles. This will clean out and help break in the transmission.
After the break in period, we recommend using 2 quarts of Pennzoil 80W-90 gear lubricant. We have had good results using Pennzoil gear lube.
We highly recommend changing the gear lubricant every 20-25,000 miles.