I'm getting ready to replace the lube in my 12-bolt Eaton posi differential. After reading over threads on this topic I think I need to add the posi lube even though I'm going synthetic. Is this correct? (If I do understand correctly only Amsoil 2000 does not require the additive.)

Is the posi additive something your local auto parts store like O'Riellys or AutoZone will have? Any particular brand I should look for?

Thanks gang!

You can try it without the additive if you want and add it later if you need it. Get the GM additive #1052358 at your GM dealer.

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'69 RS/SS396 pro street
427/4spd/9"
Byars Performance
High Performance Drive Train Parts And Service
www.lubedealer.com/biggearhead (http://www.lubedealer.com/biggearhead)

Thank you BGH!

I'm going to play it safe and go ahead and put the additive in.

Thanks again!