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Discussion Starter · #1 ·
I searched on this, but I'm still confused. I can hear a slight chatter from the rear when I make a hard turn at slow, parking lot speeds. I have decided on Royal Purple, but I'm not sure on the viscosity. I think I saw an even split on the 80W-90 versus 75W-140. Which is correct? Would it make a difference since it doesn't get driven in the winter?
Thanks,
Bruce
 

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Everything I have read and all of the receommendations I have received said to use 75W-140 fluid. That is what I put in mine when I changed it.

I would not sweat a "slight" noise when conducting a tight slow turn with Limited Slip Diff. You are making the clutches slip to accomodate the difference in turning radius. Check the fluid level to be sure it is not real low.
 

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I have an Eaton Posi diff and I just had the same type of chatter going on. I had the rear diff fluid changed by a shop, I am not sure exactly what fluid they put in there but I had them put the Ford friction modifier in there that several people on a few forums suggested and after driving a few miles and letting it sit for a few hours, the sound was gone. I would think that the friction modifier was what made the difference not necessarily the fluid.
 

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Discussion Starter · #4 ·
TRUEBLUE3934 said:
Everything I have read and all of the receommendations I have received said to use 75W-140 fluid. That is what I put in mine when I changed it.

I would not sweat a "slight" noise when conducting a tight slow turn with Limited Slip Diff. You are making the clutches slip to accomodate the difference in turning radius. Check the fluid level to be sure it is not real low.
I'm sure you are right, but its never been changed (31k), so I'll do it as a precaution. I'll go with the 75W-140 Royal Purple.
Thanks,
Bruce
 

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I went with 75w-140 since it's the factory recommendation.
I just bought the SuperTech Synthetic stuff from WalMart as it was the only thing I could find that matched the factory specs from the local stores. I also of course added the modifier.
 
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