[QUOTE=The other Joe;13995887]I would not say that. My tucks have over 150k on them and the LS works fine

 

brad ... can i infer from your reply that ;

A) i do have a limited slip rear end, and
B) you think that synthetic is the way to go ?

by the way, my truck has a little under 100k miles on it; don't know whether the LS works ( if it has one). changing lube only because i have no idea whether it has ever been done and also because i have a leaking axle seal.

thanks.

 

The easies way to tell if you have LS or not is the tag on the rear axle

typical the bolt that holds it on the diff cover, covers the 1st digit so you will see..

L10 or L55 if it is limited slip

10 or 55 if it is open

I always run synthetic in the rear axle, because that is what it calls for

 

Picked up some Lucas heavy duty 85w140 and the diff cover gaskets that came in at the parts store.

I don't know about at what point the LS wears out, but my 10.25 is a locker so it's not a concern for my truck.

 

thanks for the info; i'll check it out.
i find the haynes manual thoroughly confusing regarding rear ends; it mentions ford and dana, but nothing about sterling.

 

Sterling is Ford's axle. The Ford axle plant is in a city called Sterling Heights, MI.

 

GoinBoarding ... thanks ... that makes things much clearer to me now !

 

What a timely thread. I just noticed today that my limited slip rear diff is doing nothing but slipping.

Yes, the tag says it's a limited lip. I changed the diff oil a few months ago. The oil I bought has the friction additive in it, so I didn't add any. Would more friction additive help?

 

[QUOTE=Diesel_Brad;13996109]Brad, 150k is great for a factory clutches. I have heard many reports of those being bad by 70k or so.
Maybe the key is proper servicing when the Truck has 30k miles or so.
I know many people never change their diff oils.

I haven't checked if mine works on the new truck yet. It has 170 k so I am not hopeful it works. It would be a pleasant surprise for sure.

Thanks,
Joe W.

 

Actually, more modifier hurts. The friction modifier is to make the clutches slip smoothly without jittering.
Without the additive, the LSD is harsh and doesn't disengage as well.

The life of a LSD diff depends on how it's driven. If you spin the tires excessively, and it catches and only one tire spins, you're burning the clutches. Kinda like slipping the clutch in your trans, it can only take so much before they glaze over.

 

75w90 Amsoil is ok.