Rear Diff Fluid Change Question

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Peter V

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I'll be changing my fluids this weekend, to include front/rear/TC/tranny. When changing the rear diff, the manual instructs to use Mercon SP which I purchased (Amsoil brand). The question is, do I need to add any type of rear diff additive? I read somewhere and watched some DIY videos that also included additives for the limited slip, etc. The manual doesn't say to add anything so I am assume, use ONLY Mercon SP?



BTW, I own a Gen2 4.6L 4x4. Thanks in advance!
 
If it's a OEM limited slip, yes. And I've read that the Ford additive should be used (even by those using aftermarket synthetics).
 
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I stand correct members...it's not MERCON SP that I am using. It's 75w140 gear lube for the rear diff.



***Sorry for the confusion as I was referencing the ATF fluid instead of the REAR DIFF***
 
I'm the AMSOIL dealer who helps sponsor this site. IF you have a LS diff the additive is not normally needed when using our gear lubes. You can if you want, and AMSOIL makes a product called Slip Lock.
 
Thanks Vic for the confirmation...I didn't know you were the local dealer. I'll be picking up some before I change all the fluids tomorrow.
 
My personal experiance with ford traction-lok rear differential. I always got clutch chatter, until I added the 8oz, bottle of ford modifier. Never used amsoil, but other brands of synthetic and non. Still chattered until I put the ford modifier in it. IMO dont short change it. Only a couple of $$ for what definitly works.

Almost ruined my stang rebuild 'cause Mobil said, it was in there.

Same goes' for friends fords. We learned our leasons. Pete use Vic's lube is ok. I will always stick to the ford modifier, though.
 
Completed the front/rear/TC fluid changes today. All in all, not too difficult except getting to a couple of the front diff bolts. I did end up purchasing and using the Ford's additive just to be on the safe side.



Thanks for all the help! Next...is the a full tranny fluid/filter change.
 
Gen 2's do not have Traction-Lock diffs because they have traction control instead. You do not need an additive. I change the rear myself every 30k with Mobil 1 75w-140. Front every 50k at the quicky-lube with 75w-90.
 
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