75-140 gear oil?

[360cid]

Just did a fluid change in my '04 X 8.8 rear with Redline 75-140 and it seemed to be like molasses(SP?)! What I drained out of it at 90,x.. miles, it seemed to take as long to fill as it did to drain! My main question is why 75-140 instead of the 75-90 like it says on the diff cover?

 

[techieman33]

the 75-140 is for the limited slip diffs, if you have an open diff 75-90 would have been fine. Nothing wrong with the 140 though in an open diff.