changing posi lube

[toplessHO]

going to do a flush of posi unit,son works at a mobil kwik lube,
and hes suggesting removal of all old lube and replacement with mobil synthetic gear lube.
Do I need to add GM posi additive?
rear has about 60 K on it now and posi unit acts just fine.

[502ci]

Does the mobil synthetic say it has a limited slip additive? If not you must add it.

[toplessHO]

dont know will check and see.
Since this is a store that is franchised by Mobil I would think
they know but i do know that some reports in past of using
conventional hipo gear oil has said it didnt need additive but in fact
GM posis did act up and cleared right up with one or 2 bottles fo supplement.

[keliente]

Yes you will need the additive no matter what fluid you choose.