ford 8.8 lsd and modifier

[Riptide]

Is there any harm in adding a bottle of ford friction modifier to the differential? I have valvoline synth in there and it says it already has additives. Has anyone dumped extra modifier in there and had a problem because of it?

Long story short - got a clunk out of the rear of my car when going up into my driveway that I can't get rid of. Most of the usual suspects have already been gone over and it persists.

 

[msmoke00]

No issue. I have had two 9.75" Ford rears that I have always added the extra friction modifier into even with Amsoil lube that has it in it. The extra modifier might shorten the oil life, but I think that's better than finding out there's chatter. Since you already have a clunk, you could try it without and if it persists just add it in.

 

[EricF]

I've always added a motorcraft or redline friction modifier (all 4 oz) and never have had a problem. I do use the Valvoline WB 80w90, it's supposed have the additive in it already but I just add the friction modifier just because.

 

[exranger06]

I also have a Ford 8.8 with LS. I use the Valvoline synthetic with no extra modifier at all and haven't had any problems.