Fluid Advice - 98 GC Diffs

The 5.9's all have the same aluminum Dana 44 with a limited slip, and a pretty tight one too, judging by what my wife's 5.9 does to our curved gravel driveway every time she drives on it. It makes more of a mess that my detroit does, spitting gravel and digging trenches, even after 140000km of use.

The additive is referred to as "friction modifier", and some will say that any gear lube marked as suitable for limited slips has enough of this modifier in it. Since a little bottle of the additive is pretty cheap at the dealer and lasts for several diff lube changes, I've always added it anyway so I don't know what the effects of not using any might be.

/Peter

I understand that not using any wears out the clutch packs quickly.

If so, that might explain why the clutch packs in my wife's 5.9 are obviously not worn out - it's always had the Mopar additive used.

/Peter

It will make them chatter and grab on turns. I don't know about wearing out. Most (sane) people can't stand the chatter and will get it fixed before it does any damage. I installed an Auburn limited slip once, and put some aftermarket "limited slip differential gear lubricant" in it. It grabbed like crazy on the corners. That is when I decided that there is no replacement for the OEM "friction modifier", whatever it has in it.

Earle

Thanks for the help.

That it is a limited slip does explain a lot about the bind I get in tight corners.

Shou;d I assume the rear is also limited slip?

Thanks again.

Only the rear is limited slip, not the front. The "bind" you are referring to is more likely due to the fact that it is all-wheel-drive rather than because of a rear limited slip. The viscous coupling in the transfer case gets a good workout when you turn tight corners.

/Peter