I saw only one or two good responses.

Just rean 80 or 90w gear oil. Of any brand. I for a while ran the cheapest gear oil I could find and had no problems.

Now, having a good job, I run NOTHING but royal purple and lucas products.

Switching mostly to Lucas now, however I got gains all across the board with Royal Purple.

you CAN run motor oil in the trans, none of the 10w-30 crap. Just run SAE 30 or something to that effect no "number W" in it. Otherwise stick with gear oil.